Vulnerability CVE-2024-26875
Published: 2024-04-17

Description:
In the Linux kernel, the following vulnerability has been resolved:

media: pvrusb2: fix uaf in pvr2_context_set_notify

[Syzbot reported]
BUG: KASAN: slab-use-after-free in pvr2_context_set_notify+0x2c4/0x310 drivers/media/usb/pvrusb2/pvrusb2-context.c:35
Read of size 4 at addr ffff888113aeb0d8 by task kworker/1:1/26

CPU: 1 PID: 26 Comm: kworker/1:1 Not tainted 6.8.0-rc1-syzkaller-00046-gf1a27f081c1f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc4/0x620 mm/kasan/report.c:488
kasan_report+0xda/0x110 mm/kasan/report.c:601
pvr2_context_set_notify+0x2c4/0x310 drivers/media/usb/pvrusb2/pvrusb2-context.c:35
pvr2_context_notify drivers/media/usb/pvrusb2/pvrusb2-context.c:95 [inline]
pvr2_context_disconnect+0x94/0xb0 drivers/media/usb/pvrusb2/pvrusb2-context.c:272

Freed by task 906:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:47
kasan_save_track+0x14/0x30 mm/kasan/common.c:68
kasan_save_free_info+0x3f/0x60 mm/kasan/generic.c:640
poison_slab_object mm/kasan/common.c:241 [inline]
__kasan_slab_free+0x106/0x1b0 mm/kasan/common.c:257
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2121 [inline]
slab_free mm/slub.c:4299 [inline]
kfree+0x105/0x340 mm/slub.c:4409
pvr2_context_check drivers/media/usb/pvrusb2/pvrusb2-context.c:137 [inline]
pvr2_context_thread_func+0x69d/0x960 drivers/media/usb/pvrusb2/pvrusb2-context.c:158

[Analyze]
Task A set disconnect_flag = !0, which resulted in Task B's condition being met
and releasing mp, leading to this issue.

[Fix]
Place the disconnect_flag assignment operation after all code in pvr2_context_disconnect()
to avoid this issue.

 References:
https://git.kernel.org/stable/c/ed8000e1e8e9684ab6c30cf2b526c0cea039929c
https://git.kernel.org/stable/c/d29ed08964cec8b9729bc55c7bb23f679d7a18fb
https://git.kernel.org/stable/c/ab896d93fd6a2cd1afeb034c3cc9226cb499209f
https://git.kernel.org/stable/c/eb6e9dce979c08210ff7249e5e0eceb8991bfcd7
https://git.kernel.org/stable/c/3a1ec89708d2e57e2712f46241282961b1a7a475
https://git.kernel.org/stable/c/8e60b99f6b7ccb3badeb512f5eb613ad45904592
https://git.kernel.org/stable/c/40cd818fae875c424a8335009db33c7b5a07de3a
https://git.kernel.org/stable/c/eaa410e05bdf562c90b23cdf2d9327f9c4625e16
https://git.kernel.org/stable/c/0a0b79ea55de8514e1750884e5fec77f9fdd01ee
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