CVE-2025-38227

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

media: vidtv: Terminating the subsequent process of initialization failure

syzbot reported a slab-use-after-free Read in vidtv_mux_init. [1]

After PSI initialization fails, the si member is accessed again, resulting in this uaf.

After si initialization fails, the subsequent process needs to be exited.

[1] BUG: KASAN: slab-use-after-free in vidtv_mux_pid_ctx_init drivers/media/test-drivers/vidtv/vidtv_mux.c:78 [inline] BUG: KASAN: slab-use-after-free in vidtv_mux_init+0xac2/0xbe0 drivers/media/test-drivers/vidtv/vidtv_mux.c:524 Read of size 8 at addr ffff88802fa42acc by task syz.2.37/6059

CPU: 0 UID: 0 PID: 6059 Comm: syz.2.37 Not tainted 6.14.0-rc5-syzkaller #0 Hardware name: Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:408 [inline] print_report+0xc3/0x670 mm/kasan/report.c:521 kasan_report+0xd9/0x110 mm/kasan/report.c:634 vidtv_mux_pid_ctx_init drivers/media/test-drivers/vidtv/vidtv_mux.c:78 vidtv_mux_init+0xac2/0xbe0 drivers/media/test-drivers/vidtv/vidtv_mux.c:524 vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 vidtv_start_feed drivers/media/test-drivers/vidtv/vidtv_bridge.c:239 dmx_section_feed_start_filtering drivers/media/dvb-core/dvb_demux.c:973 dvb_dmxdev_feed_start drivers/media/dvb-core/dmxdev.c:508 [inline] dvb_dmxdev_feed_restart.isra.0 drivers/media/dvb-core/dmxdev.c:537 dvb_dmxdev_filter_stop+0x2b4/0x3a0 drivers/media/dvb-core/dmxdev.c:564 dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:840 [inline] dvb_demux_release+0x92/0x550 drivers/media/dvb-core/dmxdev.c:1246 __fput+0x3ff/0xb70 fs/file_table.c:464 task_work_run+0x14e/0x250 kernel/task_work.c:227 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0xad8/0x2d70 kernel/exit.c:938 do_group_exit+0xd3/0x2a0 kernel/exit.c:1087 __do_sys_exit_group kernel/exit.c:1098 [inline] __se_sys_exit_group kernel/exit.c:1096 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1096 x64_sys_call+0x151f/0x1720 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f871d58d169 Code: Unable to access opcode bytes at 0x7f871d58d13f. RSP: 002b:00007fff4b19a788 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f871d58d169 RDX: 0000000000000064 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 00007fff4b19a7ec R08: 0000000b4b19a87f R09: 00000000000927c0 R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000003 R13: 00000000000927c0 R14: 000000000001d553 R15: 00007fff4b19a840

Allocated by task 6059: kasan_save_stack+0x33/0x60 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 poison_kmalloc_redzone mm/kasan/common.c:377 [inline] __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:394 kmalloc_noprof include/linux/slab.h:901 [inline] kzalloc_noprof include/linux/slab.h:1037 [inline] vidtv_psi_pat_table_init drivers/media/test-drivers/vidtv/vidtv_psi.c:970 vidtv_channel_si_init drivers/media/test-drivers/vidtv/vidtv_channel.c:423 vidtv_mux_init drivers/media/test-drivers/vidtv/vidtv_mux.c:519 vidtv_start_streaming drivers/media/test-drivers/vidtv/vidtv_bridge.c:194 vidtv_start_feed drivers/media/test-drivers/vidtv/vidtv_bridge.c:239 dmx_section_feed_start_filtering drivers/media/dvb-core/dvb_demux.c:973 dvb_dmxdev_feed_start drivers/media/dvb-core/dmxdev.c:508 [inline] dvb_dmxdev_feed_restart.isra.0 drivers/media/dvb-core/dmxdev.c:537 dvb_dmxdev_filter_stop+0x2b4/0x3a0 drivers/media/dvb-core/dmxdev.c:564 dvb_dmxdev_filter_free drivers/media/dvb-core/dmxdev.c:840 [inline] dvb_demux_release+0x92/0x550 drivers/media/dvb-core/dmxdev.c:1246 __fput+0x3ff/0xb70 fs/file_tabl —truncated—

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/1d5f88f053480326873115092bc116b7d14916ba
• https://git.kernel.org/stable/c/685c18bc5a36f823ee725e85aac1303ef5f535ba
• https://git.kernel.org/stable/c/72541cae73d0809a6416bfcd2ee6473046a0013a
• https://git.kernel.org/stable/c/7e62be1f3b241bc9faee547864bb39332955509b
• https://git.kernel.org/stable/c/9824e1732a163e005aa84e12ec439493ebd4f097
• https://git.kernel.org/stable/c/e1d72ff111eceea6b28dccb7ca4e8f4900b11729
• https://git.kernel.org/stable/c/f8c2483be6e8bb6c2148315b4a924c65bb442b5e
• https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
• https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html