| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
ntfs3: free the sbi after a grace period
If the "nocase" mount option ntfs3 uses custom hash and dentry compare
functions. Both access ntfs3 superblock private information in rcu
pathwalk. ntfs_put_super() and ntfs3_kill_sb() drop the info without any
rcu delay. A lookup that's still inside the filesystem when the last
reference to the mount is dropped causes a UAF. With a pathwalk held up
in ntfs_d_hash() while the last reference to the mount goes away:
BUG: KASAN: slab-use-after-free in ntfs_nls_to_utf16+0x752/0x940
Read of size 8 at addr ff1100010453c850 by task walker/99
Call Trace:
<TASK>
ntfs_nls_to_utf16+0x752/0x940
ntfs_d_hash+0x22b/0x500
link_path_walk+0x11ad/0x1d30
path_lookupat+0x63/0xb00
filename_lookup+0x1f1/0x5b0
vfs_statx+0xd7/0x3b0
[...]
Allocated by task 95:
__kmalloc_cache_noprof+0x249/0x560
ntfs_init_fs_context+0x2db/0x5a0
alloc_fs_context+0x52e/0xc70
[...]
Freed by task 98:
kfree+0x1db/0x5b0
deactivate_locked_super+0x9c/0xf0
cleanup_mnt+0x9f/0x130
task_work_run+0x131/0x250
The bug is currently masked by the grace period in namespace_unlock()
for umount(2). Keep the necessary information until the filesystem
private info is freed and free it with an rcu delay.
ntfs3_free_sbi() now runs from an rcu callback and drops the upcase
table via ntfs_put_shared(). So switch s_shared_lock over to
spin_lock_bh(). Otherwise the callback can deadlock against a task
holding the lock on the same cpu. |
| In the Linux kernel, the following vulnerability has been resolved:
ext4: free the sbi after a grace period
ext4_get_link() follows a symlink that keeps its target in a data block
in rcu pathwalk mode with ext4_getblk(EXT4_GET_BLOCKS_CACHED_NOWAIT).
That reads s_mount_state in the ASSERT() of ext4_getblk() and again in
ext4_es_lookup_extent(), and the lookup bumps the extent status hit or
miss counter, all through sb->s_fs_info.
ext4_put_super() destroys those counters, clears sb->s_fs_info and frees
the sbi without waiting for a grace period. A pathwalk that is still in
ext4_get_link() when the last reference to the mount goes away then
dereferences a NULL s_fs_info, the freed sbi or the destroyed percpu
counters.
With a pathwalk held up in ext4_get_link() while the last reference
goes away:
KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af]
RIP: 0010:ext4_getblk+0xf0/0x640
Call Trace:
<TASK>
ext4_get_link+0x26c/0x410
pick_link+0xf96/0x1780
step_into_slowpath+0x9b8/0x1250
path_lookupat+0x484/0xb00
filename_lookup+0x1f1/0x5b0
vfs_statx+0xd7/0x3b0
vfs_fstatat+0x4d/0x90
__do_sys_newfstatat+0xa0/0x100
do_syscall_64+0x10e/0x5e0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
So far that has been hard to hit. umount(2) waits for a grace period in
namespace_unlock() before it drops the mount, so only a mount whose last
reference goes away elsewhere, like the close of a file or a chdir out of
a lazily unmounted directory, can race a walker.
Keep sb->s_fs_info and free the sbi together with the extent status
counters after a grace period. Split the counters out of
ext4_es_unregister_shrinker() for that. The shrinker still gets wasted
in ext4_put_super(), the counters go with the sbi. |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry
Reset the vCPU's MMU pointer back to the root MMU if loading L2 state fails
in the "not from VM-Entry" case, i.e. when emulating RSM or handling
KVM_SET_NESTED_STATE. Failure to unwind the MMU pointer results in KVM
trying to run L1 with a nested MMU, and is especially problematic if the
vCPU manages to free its nested state before the VM crashes. Constructing
the root for a nested EPT MMU goes through vmcs12, which is dynamically
allocated/freed when nVMX is enabled/disabled. And so if the nested state
is freed with the MMU still pointing at the nested MMU, KVM will hit a NULL
pointer deref when attempting to get L1=>L2 EPTP.
BUG: kernel NULL pointer dereference, address: 0000000000000078
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 114a2d067 P4D 111743067 PUD 11141f067 PMD 0
Oops: Oops: 0000 [#1] SMP
CPU: 20 UID: 1000 PID: 1272 Comm: nested_tdp_faul Not tainted 7.3.0-rc4-8c89f11d1a99b-sink-vm #1914 PREEMPTLAZY
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]
Call Trace:
<TASK>
kvm_mmu_load+0xcd/0x870 [kvm]
kvm_arch_vcpu_ioctl_run+0x18f5/0x1f80 [kvm]
kvm_vcpu_ioctl+0x2c7/0x970 [kvm]
__x64_sys_ioctl+0x90/0xd0
do_syscall_64+0x9c/0x4d0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x47491b
</TASK>
Modules linked in: kvm_intel kvm irqbypass
CR2: 0000000000000078
---[ end trace 0000000000000000 ]---
RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]
[sean: write changelog] |
| In the Linux kernel, the following vulnerability has been resolved:
ntfs: fix FITRIM range alignment
ntfs_trim_fs() aligns the start of a free extent up to the device discard
granularity, but derives the discard length by aligning the original extent
length down. When the free extent start is not discard-aligned, adding that
length to the aligned start can extend the discard past the free extent and
into allocated clusters.
For example, with 4 KiB clusters and 32 KiB discard granularity, the free
extent [4 KiB, 36 KiB) becomes the discard range [32 KiB, 64 KiB), so
28 KiB beyond the free extent may be discarded.
Align the absolute end of the free extent down and derive the length from
the two aligned endpoints. Skip extents that contain no full discard unit.
Reproduced with a 4 KiB-cluster NTFS filesystem on scsi_debug configured
for 32 KiB discard granularity and read-zero-after-trim. Before this
change, FITRIM zeroed seven allocated 4 KiB clusters following an unaligned
32 KiB hole. With this change, the same data remains intact across FITRIM
and remount. |
| In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix data corruption with concurrent writes and O_TRUNC
cifs_do_truncate() flushes dirty pages with filemap_write_and_wait()
and truncates the file on the server, but in the old code both
operations ran without holding i_rwsem or invalidate_lock. A
concurrent buffered write via netfs_perform_write() -- which only
needs i_rwsem shared -- could dirty new pages after the flush but
before the local truncation, and those pages would be silently
discarded by cifs_setsize() -> truncate_pagecache().
Fix by acquiring inode_lock (exclusive i_rwsem) and
filemap_invalidate_lock at the top of cifs_do_truncate(), so the
entire flush-truncate-resize sequence is atomic with respect to:
- buffered writes (blocked by exclusive i_rwsem, since
netfs_start_io_write takes i_rwsem shared),
- read page faults (blocked by exclusive invalidate_lock, since
filemap_fault takes it shared),
- writeback collection (blocked by netfs_wb_begin/netfs_wb_end
around the server truncate and local resize, since
netfs_writepages also acquires the wb lock). |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fill in FileSysIdentifier in FS_POSIX_INFORMATION
smb2_get_info_filesystem() reports 56 bytes for FS_POSIX_INFORMATION,
that is the whole of FILE_SYSTEM_POSIX_INFO, but never assigns
FileSysIdentifier. Those eight bytes go to the client as they are found
in the response buffer.
The buffer is zeroed on allocation, so a standalone request leaks
nothing. A compound request can leak: the offset of the next response
is advanced by the length pinned for the previous one, so a reply that
was written into the buffer and then dropped in favour of the short
error response of smb2_set_err_rsp() stays there, and the next reply is
laid over it with only the header cleared.
Report the file system id statfs() returned, which is what the field is
for. FileSysIdentifier is __le64 and f_fsid is a pair of ints, so
assemble the value first, val[0] as the low half, and convert it on the
way out. |
| In the Linux kernel, the following vulnerability has been resolved:
net: psp: do not inherit the Rx association on clone
sk->psp_assoc sits past sk_dontcopy_end, so sock_copy() copies it into
every socket accepted from a listener without taking a reference, while
inet_sock_destruct() puts for every inet socket. psp_twsk_init() does
refcount_inc() for the timewait socket, so a child closing through
TIME_WAIT cancels its own put and leaves the association with one
reference and N timewait sockets holding the same pointer. Closing the
listener frees it, and the timewait timers then put freed memory.
Rejecting the association on a listening socket is not sufficient: a socket
can acquire one while established and then be turned back into a listener,
because tcp_disconnect() leaves sk->psp_assoc in place.
BUG: KASAN: slab-use-after-free in psp_twsk_assoc_free+0x6f/0xf0
Write of size 4 at addr ffff888110f9255c by task swapper/7/0
psp_twsk_assoc_free+0x6f/0xf0
inet_twsk_put+0xda/0x1b0
call_timer_fn+0x53/0x2e0
__run_timers+0x764/0xa80
Freed by task 99:
kfree+0x1a7/0x500
process_one_work+0x7ec/0x1100
An association carries a per-connection SPI and key, so a child must not
inherit the parent's. Clear it on clone. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/userq: actually validate userq BOs
This was supposed to loop over the individual evicted list, as the
kernel and always_valid evicted lists were already handled in
amdgpu_vm_validate.
Without this, BOs that were created and evicted before a userq was made
would never end up in an eviction fence rearm.
Also add the missing ref to the BO before drm_exec locks and refs it.
(cherry picked from commit 18decfc9e8cc0fa70b6de9944cc27a37729edfbd) |
| In the Linux kernel, the following vulnerability has been resolved:
s390/pci: Fix leak of uninitialized kernel data in SCLP report
While report_error_write() checks that the provided buffer is at least
as large as the header struct, but not that it is large enough to
contain the report with the length claimed by report->length. If
user-space provides a short buffer, meaning a larger report->length than
the actually written payload, up to around 4K of kernel data from past
the kmalloc(len + 1) sized buffer allocated in kernfs_fop_write_iter()
will leak into the SCLP report.
However, as the entity processing the SCLP is privileged and able to
access at least the page including the report, this does not leak data
that entity could not access but it is still an out of bounds read and
a malformed error report that should be rejected. |
| In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix hist trigger timestamps for buffered events
Syzkaller triggered a WARN_ON_ONCE(!nest) warning:
WARNING: kernel/trace/ring_buffer.c:821 at ring_buffer_event_time_stamp
Call trace:
ring_buffer_event_time_stamp
hist_field_timestamp
hist_fn_call
event_hist_trigger
event_triggers_call
__event_trigger_test_discard
trace_event_buffer_commit
do_trace_event_raw_event_sched_switch
trace_event_raw_event_sched_switch
The warning is probabilistically reproducible and is related to syzkaller
executing the following commands:
echo 'prev_pid == 999999' > events/sched/sched_switch/filter
echo 'hist:keys=common_timestamp' > events/sched/sched_switch/trigger
The specific triggering process is as follows:
CPU 0 CPU 1
(context switching) (echo 'hist:keys=common_timestamp' > \
events/sched/sched_switch/trigger)
do_trace_event_raw_event_##call
trace_event_buffer_lock_reserve
if (!tr->no_filter_buffering_ref &&
trace_file->flags & EVENT_FILE_FL_FILTERED)
return entry; // return directly
event_hist_trigger_parse
hist_register_trigger
tracing_set_filter_buffering(file->tr, true);
tr->no_filter_buffering_ref++;
__trace_buffer_lock_reserve
rb_start_commit
local_inc(&cpu_buffer->committing); // skipped and not executed
trace_event_buffer_commit
__event_trigger_test_discard
event_triggers_call
event_hist_trigger
hist_fn_call
hist_field_timestamp
ring_buffer_event_time_stamp
nest = local_read(&cpu_buffer->committing);
WARN_ON_ONCE(!nest) // trigger warning
The root cause is that when an event file has a filter attached and the
hist trigger has not yet been attached, trace_event_buffer_lock_reserve()
writes the event into the per-CPU trace_buffered_event temp buffer instead
of reserving it in the ring buffer, so cpu_buffer->committing is not
incremented. When the event is later processed at commit time by a hist
trigger, hist_field_timestamp() -> ring_buffer_event_time_stamp() sees a
zero committing count, triggering WARN_ON_ONCE(!nest).
tracing_event_time_stamp() was added by commit d8279bfc5e959 ("tracing:
Add tracing_event_time_stamp() API") for exactly this case: if the event
is the per-CPU trace_buffered_event, it returns the current ring buffer
timestamp. But it never gained a caller. Use it in hist_field_timestamp(),
so that a hist trigger that races onto a buffered event records the
current time, which is only marginally later than when the event was
recorded, instead of warning and recording a bogus timestamp. |
| In the Linux kernel, the following vulnerability has been resolved:
tracing: Fix crash in print_graph_function_event()
tracing_set_tracer() assigns the flags of the newly selected tracer
with:
tr->current_trace_flags = t->flags ? : t->tracer->flags;
If the new tracer defines neither static flags nor default flags, like
hwlat, irqsoff or wakeup, add_tracer() has no per instance flags copy
for it, and both operands are NULL, so tr->current_trace_flags ends up
being NULL as well.
The ring buffer is not cleared when switching tracers: it is reset
inside tracer_init(), after current_trace_flags was already assigned.
If the buffer still holds function_graph entries of the previous
tracer, printing one of them dereferences the NULL pointer. This was
hit by cat trace during an ftrace stress test:
BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
RIP: 0010:print_graph_function_event+0xe/0x20
Call Trace:
s_show+0x4d/0x110
seq_read_iter+0x2d4/0x490
seq_read+0x130/0x170
vfs_read+0xb5/0x370
ksys_read+0x6d/0xe0
do_syscall_64+0xbc/0x450
The snapshot buffer is not reset at all, so this can be reproduced
without a race:
echo function_graph > /sys/kernel/tracing/current_tracer
echo 1 > /sys/kernel/tracing/snapshot
echo hwlat > /sys/kernel/tracing/current_tracer
cat /sys/kernel/tracing/snapshot
Rather than teaching every user of tr->current_trace_flags about this
corner case, make sure it is never NULL: when the newly selected
tracer has no flags at all, tracing_set_tracer() falls back to a
static empty no_tracer_flags. run_tracer_selftest() can hit the same
case, so the same fallback is added there too. The existing users
already handle opts == NULL, so these tracers keep behaving as before. |
| In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix use-after-free of a destroyed user DSQ by a deferred reenqueue
A deferred reenqueue can read a freed user DSQ. The request stays on its
CPU's deferred list until run_deferred() takes it, and the RCU callback that
frees the DSQ assumes that the grace period has flushed it, so exit_dsq()
checks the per-CPU node without the deferred list lock. A grace period waits
for readers in flight, not for a pending run_deferred(). A run_deferred()
which starts after the grace period began can detach the request right
before the callback looks and then read the freed DSQ's id.
Cancel the pending requests before the grace period instead. The irq work
that frees the DSQ unlinks every CPU's request under the per-CPU deferred
list lock, and schedule_dsq_reenq() ignores a new request under the same
lock once the id is invalid. Only a run_deferred() that started before the
grace period can hold a request, and it runs with IRQs disabled, so the
grace period waits for it and nothing touches the DSQ after the callback. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/xe: Don't transfer shrinker pages for pinned bos on purgeable state change
Pinned bos have their pages removed from the shrinker's shrinkable /
purgeable counts on pin, and added back on unpin according to the
bo's purgeable state at that time.
However, xe_bo_set_purgeable_shrinker() unconditionally transfers
pages between the shrinkable and purgeable counts. If the purgeable
state of a pinned bo changes, for example by userspace madvising
DONTNEED on a VMA of a bo that is also pinned as a scanout buffer,
this underflows one count and, after unpin, leaves the other one
permanently inflated.
Only update the purgeable flag for pinned bos, and leave the page
accounting to unpin.
(cherry picked from commit afe6bc012034123fd838328668e609bf57e46bd3) |
| In the Linux kernel, the following vulnerability has been resolved:
ipv4: avoid divide by zero in fib_rebalance
fib_rebalance() computes the total eligible nexthop weight in one pass
and programs upper bounds in a second pass. A concurrent change to
ignore_routes_with_linkdown can make the first pass return zero while
the second pass sees an eligible nexthop, resulting in division by zero.
If the first pass reports a zero total, set each nexthop upper bound to
-1 and skip the division. This matches the IPv6 fix in commit
d2c26c2911dd ("ipv6: avoid divide by zero in rt6_multipath_rebalance")
and preserves the lock-free rebalance path. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/i915/dmc: Add sanity check for DMC load address
For DMC firmware header version 3, the firmware load address is stored
in dmc_info->start_mmioaddr and later used by dmc_load_program().
Unlike the MMIO address table, the firmware load address is not
validated. Add a sanity check to ensure it is within the valid range.
BSpec: 69671, 68378
(cherry picked from commit 5e47ee5c76ca9becde8df4ad5202845b7ffcbc4c) |
| In the Linux kernel, the following vulnerability has been resolved:
drm/exec: don't immediately add prelocked obj to array of locked objs
When a contention is detected the drm_exec object grabs a reference to
the contended object, unlocks all other objects and pre-locks the
contended one before anything else.
The problem is that it is possible that this pre-locked object was about
to be destroyed and drm_exec is now holding the last reference to it.
So we never actually see this pre-locked object again to be explicitly
locked and so also never reserve a slot for a dma_fence object on it.
Should the driver now use drm_exec_for_each_locked_object() to add a new
fence to all locked objects we eventually see a warning or even a
BUG_ON() to prevent random memory corruption.
Fix this by keeping the prelocked object out of the array of locked objs
until it was explicitly mentioned by the driver again.
If the prelocked object is never mentioned again by the driver
just unlock and drop the reference at the end of the locking loop. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: fix GEM object leak on ENOMEM in userptr ioctl
When amdgpu_hmm_range_alloc() fails amdgpu_gem_userptr_ioctl() returns
-ENOMEM right away and skips the cleanup every other error path goes
through. The GEM object, the bo->parent reference on the VM root and the
MMU notifier registration are all left behind.
Use release_object here, not user_pages_done, range is still NULL at
this point.
(cherry picked from commit bbe739e407a542073ec1a7872b14843566b4919e) |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: don't drop the runtime PM reference twice in amdgpu_gpr
amdgpu_debugfs_gpr_read() drops its runtime PM reference right after
reading the wave registers. When copying them to userspace fails, it
jumps to the err label, which drops the reference a second time. A read
into a bad buffer on Navi31 either steals a reference somebody else
holds (power/runtime_usage goes from 1 to 0) or underflows the count:
amdgpu 0000:03:00.0: Runtime PM usage count underflow!
The registers are already in the kernel buffer at that point, so finish
the hardware access first and copy the buffer with a single
copy_to_user() instead of the put_user() loop with its own error path.
(cherry picked from commit 31035bbd74f7c3e10c163db875b8e67f8b50ee6a) |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: libiscsi: Validate the ITT reflected in a Reject PDU
A Reject PDU carries a copy of the header it rejects, and
iscsi_handle_reject() takes the ITT out of that copy to find the task to
clean up:
memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
...
task = iscsi_itt_to_task(conn, rejected_pdu.itt);
That value is whatever the target put there. iscsi_itt_to_task() bounds
the index against cmds_max and checks nothing else, so any task in the
pool can be named, and iscsi_nop_out_rsp() then completes it.
An index that has never been used gives a NULL task->conn: the pool is
zeroed at session setup and conn is assigned only when a task is
allocated. If the task was used and returned, iscsi_complete_task() hits
its WARN_ON_ONCE(task->state == ISCSI_TASK_FREE) and the refcount
underflows. An in-flight SCSI command is completed as successful - a 1
MiB read returned 1048576 with none of its buffer written and no
warning.
Validate the reflected ITT the way iscsi_itt_to_ctask() validates a
command ITT, and require the task to be in flight and not a SCSI
command.
[ 6.248477] Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN NOPTI
[ 6.249357] KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
[ 6.249951] CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted 7.2.0-rc5-ISCSI1-gf5098b6bae76 #1 PREEMPT(lazy)
[ 6.250718] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 6.251616] RIP: 0010:iscsi_nop_out_rsp.constprop.0+0x46/0x160
[ 6.252043] Code: c1 ea 03 48 83 ec 08 80 3c 02 00 0f 85 f5 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8b 6b 58 48 8d 7d 60 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 c0 00 00 00 48 8b 45 60 48 39 c3 74 50 48 b8 00
[ 6.252813] RSP: 0018:ffff88806c907b80 EFLAGS: 00010206
[ 6.253042] RAX: dffffc0000000000 RBX: ffff88800607e000 RCX: ffffffff8d571a25
[ 6.253345] RDX: 000000000000000c RSI: ffff88806c907c38 RDI: 0000000000000060
[ 6.253642] RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff235a504
[ 6.253947] R10: 0000000000000003 R11: 7463656e6e6f6320 R12: 0000000000000000
[ 6.254251] R13: 0000000000000000 R14: ffff88806c907c38 R15: 0000000000000000
[ 6.254549] FS: 0000000000000000(0000) GS:ffff8880d95bc000(0000) knlGS:0000000000000000
[ 6.254887] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6.255140] CR2: 00007fc393e8ffc0 CR3: 0000000005252006 CR4: 0000000000770ef0
[ 6.255439] PKRU: 55555554
[ 6.255564] Call Trace:
[ 6.255674] <IRQ>
[ 6.255768] __iscsi_complete_pdu+0x18bf/0x22a0
[ 6.256733] iscsi_complete_pdu+0x54/0xa0
[ 6.256905] iscsi_tcp_data_recv_done+0xf4/0x250
[ 6.257103] iscsi_tcp_recv_skb+0x31e/0xec0
[ 6.257680] iscsi_sw_tcp_recv+0x12f/0x390
[ 6.258061] __tcp_read_sock+0x1ab/0x810
[ 6.258853] iscsi_sw_tcp_data_ready+0x18b/0x510
[ 6.259808] tcp_data_queue+0x1f13/0x4cd0
[ 6.260567] tcp_rcv_established+0x8a5/0x3a00
[ 6.261931] tcp_v4_do_rcv+0x449/0x960
[ 6.262269] tcp_v4_rcv+0x2245/0x3bc0 |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: xen/scsifront: Check for a NULL shadow entry on a backend response
scsifront_do_response() validates the rqid in a backend response against
VSCSIIF_MAX_REQS before using it to index info->shadow[], but then
dereferences the entry to test ->inflight without checking that the slot
is populated. Shadow slots are NULL before a command is submitted (the
host private area is zeroed at allocation) and are reset to NULL in
_scsifront_put_rqid() once a request completes, so an in-range rqid that
does not correspond to an outstanding request makes the frontend
dereference a NULL pointer.
A malicious or buggy backend can thus crash the guest by returning a
response whose rqid is in range but not in flight -- for example a
spurious response before any command has been issued, or a duplicate of
one already completed. The ring has only VSCSIIF_MAX_REQS (16) slots,
so before the first command every in-range rqid selects a NULL slot.
Reject a response whose shadow slot is not populated. |
