CVE-2024-38601
ring-buffer: Fix a race between readers and resize checks
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Fix a race between readers and resize checks
The reader code in rb_get_reader_page() swaps a new reader page into the
ring buffer by doing cmpxchg on old->list.prev->next to point it to the
new page. Following that, if the operation is successful,
old->list.next->prev gets updated too. This means the underlying
doubly-linked list is temporarily inconsistent, page->prev->next or
page->next->prev might not be equal back to page for some page in the
ring buffer.
The resize operation in ring_buffer_resize() can be invoked in parallel.
It calls rb_check_pages() which can detect the described inconsistency
and stop further tracing:
[ 190.271762] ------------[ cut here ]------------
[ 190.271771] WARNING: CPU: 1 PID: 6186 at kernel/trace/ring_buffer.c:1467 rb_check_pages.isra.0+0x6a/0xa0
[ 190.271789] Modules linked in: [...]
[ 190.271991] Unloaded tainted modules: intel_uncore_frequency(E):1 skx_edac(E):1
[ 190.272002] CPU: 1 PID: 6186 Comm: cmd.sh Kdump: loaded Tainted: G E 6.9.0-rc6-default #5 158d3e1e6d0b091c34c3b96bfd99a1c58306d79f
[ 190.272011] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552c-rebuilt.opensuse.org 04/01/2014
[ 190.272015] RIP: 0010:rb_check_pages.isra.0+0x6a/0xa0
[ 190.272023] Code: [...]
[ 190.272028] RSP: 0018:ffff9c37463abb70 EFLAGS: 00010206
[ 190.272034] RAX: ffff8eba04b6cb80 RBX: 0000000000000007 RCX: ffff8eba01f13d80
[ 190.272038] RDX: ffff8eba01f130c0 RSI: ffff8eba04b6cd00 RDI: ffff8eba0004c700
[ 190.272042] RBP: ffff8eba0004c700 R08: 0000000000010002 R09: 0000000000000000
[ 190.272045] R10: 00000000ffff7f52 R11: ffff8eba7f600000 R12: ffff8eba0004c720
[ 190.272049] R13: ffff8eba00223a00 R14: 0000000000000008 R15: ffff8eba067a8000
[ 190.272053] FS: 00007f1bd64752c0(0000) GS:ffff8eba7f680000(0000) knlGS:0000000000000000
[ 190.272057] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 190.272061] CR2: 00007f1bd6662590 CR3: 000000010291e001 CR4: 0000000000370ef0
[ 190.272070] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 190.272073] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 190.272077] Call Trace:
[ 190.272098] <TASK>
[ 190.272189] ring_buffer_resize+0x2ab/0x460
[ 190.272199] __tracing_resize_ring_buffer.part.0+0x23/0xa0
[ 190.272206] tracing_resize_ring_buffer+0x65/0x90
[ 190.272216] tracing_entries_write+0x74/0xc0
[ 190.272225] vfs_write+0xf5/0x420
[ 190.272248] ksys_write+0x67/0xe0
[ 190.272256] do_syscall_64+0x82/0x170
[ 190.272363] entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 190.272373] RIP: 0033:0x7f1bd657d263
[ 190.272381] Code: [...]
[ 190.272385] RSP: 002b:00007ffe72b643f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
[ 190.272391] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f1bd657d263
[ 190.272395] RDX: 0000000000000002 RSI: 0000555a6eb538e0 RDI: 0000000000000001
[ 190.272398] RBP: 0000555a6eb538e0 R08: 000000000000000a R09: 0000000000000000
[ 190.272401] R10: 0000555a6eb55190 R11: 0000000000000246 R12: 00007f1bd6662500
[ 190.272404] R13: 0000000000000002 R14: 00007f1bd6667c00 R15: 0000000000000002
[ 190.272412] </TASK>
[ 190.272414] ---[ end trace 0000000000000000 ]---
Note that ring_buffer_resize() calls rb_check_pages() only if the parent
trace_buffer has recording disabled. Recent commit d78ab792705c
("tracing: Stop current tracer when resizing buffer") causes that it is
now always the case which makes it more likely to experience this issue.
The window to hit this race is nonetheless very small. To help
reproducing it, one can add a delay loop in rb_get_reader_page():
ret = rb_head_page_replace(reader, cpu_buffer->reader_page);
if (!ret)
goto spin;
for (unsigned i = 0; i < 1U << 26; i++) /* inserted delay loop */
__asm__ __volatile__ ("" : : : "memory");
rb_list_head(reader->list.next)->prev = &cpu_buffer->reader_page->list;
..
---truncated---
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ring-buffer: corrige una ejecución entre lectores y cambia el tamaño de las comprobaciones. El código del lector en rb_get_reader_page() intercambia una nueva página del lector en el búfer circular haciendo cmpxchg en old->list.prev ->siguiente para apuntar a la nueva página. Después de eso, si la operación es exitosa, old->list.next->prev también se actualiza. Esto significa que la lista doblemente enlazada subyacente es temporalmente inconsistente, página->anterior->siguiente o página->siguiente->anterior podría no ser igual a la página para alguna página en el búfer circular. La operación de cambio de tamaño en ring_buffer_resize() se puede invocar en paralelo. Llama a rb_check_pages(), que puede detectar la inconsistencia descrita y detener el seguimiento: [190.271762] ------------[ cortar aquí ]------------ [ 190.271771] ADVERTENCIA: CPU: 1 PID: 6186 en kernel/trace/ring_buffer.c:1467 rb_check_pages.isra.0+0x6a/0xa0 [190.271789] Módulos vinculados en: [...] [190.271991] Módulos contaminados descargados: intel_uncore_frequency(E) :1 skx_edac(E):1 [ 190.272002] CPU: 1 PID: 6186 Comm: cmd.sh Kdump: cargado Contaminado: GE 6.9.0-rc6-default #5 158d3e1e6d0b091c34c3b96bfd99a1c58306d79f [ 190.272011] Nombre del hardware: PC estándar QEMU (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552c-rebuilt.opensuse.org 01/04/2014 [ 190.272015] RIP: 0010:rb_check_pages.isra.0+0x6a/0xa0 [ 190.272023] Código: [.. .] [ 190.272028] RSP: 0018:ffff9c37463abb70 EFLAGS: 00010206 [ 190.272034] RAX: ffff8eba04b6cb80 RBX: 00000000000000007 RCX: ffff8eba01f13d80 [ 19 0.272038] RDX: ffff8eba01f130c0 RSI: ffff8eba04b6cd00 RDI: ffff8eba0004c700 [ 190.272042] RBP: ffff8eba0004c700 R08: 0000000000010002 R09: 00000000 [ 190.272045] R10: 00000000ffff7f52 R11: ffff8eba7f600000 R12: ffff8eba0004c720 [ 190.272049] R13: ffff8eba00223a00 R14: 0000000000000008 R15: ffff8eba067a8000 [ 190.272053] FS: 00007f1bd64752c0(0000) GS:ffff8eba7f680000(0000) knlGS:000000000000000000 [ 190.272057] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 190.272061] CR2: 00007f1bd6662590 CR3: 000000010291e001 CR4: 0000000000370ef0 [ 190.272070] DR0: 000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 190.272073] DR3: 0000000000000000 DR6: 00000000ffe0ff0 DR7: 0000000000000400 [ 190 .272077] Seguimiento de llamadas: [190.272098 ] [ 190.272189] ring_buffer_resize+0x2ab/0x460 [ 190.272199] __tracing_resize_ring_buffer.part.0+0x23/0xa0 [ 190.272206] tracing_resize_ring_buffer+0x65/0x90 [ 190.272216] _entries_write+0x74/0xc0 [ 190.272225] vfs_write+0xf5/0x420 [ 190.272248 ] ksys_write+0x67/0xe0 [ 190.272256] do_syscall_64+0x82/0x170 [ 190.272363] Entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 190.272373] RIP: 0033:0x7f1bd657d26 3 [ 190.272381] Código: [...] [ 190.272385] RSP: 002b:00007ffe72b643f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 [ 190.272391] RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f1bd657d263 [ 190.272395] RDX: 0000000 000000002 RSI: 0000555a6eb538e0 RDI: 0000000000000001 [ 190.272398] RBP: 0000555a6eb538e0 R08: 000000000000000a R09: 0000000000000000 [ 190.272401] R10: 0000555a6eb55190 R11: 0000000000000246 R12 : 00007f1bd6662500 [ 190.272404] R13: 0000000000000002 R14: 00007f1bd6667c00 R15: 00000000000000002 [ 190.272412] [ 4] ---[ end trace 0000000000000000 ]--- Tenga en cuenta que ring_buffer_resize() llama a rb_check_pages() solo si el trace_buffer principal tiene grabación desactivada. El reciente commit d78ab792705c ("rastreo: detener el rastreador actual al cambiar el tamaño del búfer") hace que ahora sea siempre el caso, lo que hace que sea más probable experimentar este problema. No obstante, la ventana para llegar a esta ejecución es muy pequeña. Para ayudar a reproducirlo, se puede agregar un bucle de retardo en rb_get_reader_page(): ret = rb_head_page_replace(reader, cpu_buffer->reader_page); if (!ret) ir a girar; for (unsigned i = 0; i < 1U << 26; i++) /* bucle de retardo insertado ---truncado---
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-06-18 CVE Reserved
- 2024-06-19 CVE Published
- 2024-06-20 EPSS Updated
- 2024-11-05 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
- CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CAPEC
References (12)
| URL | Tag | Source |
|---|---|---|
| https://git.kernel.org/stable/c/659f451ff21315ebfeeb46b9adccee8ce1b52c25 | Vuln. Introduced |
| URL | Date | SRC |
|---|
| URL | Date | SRC |
|---|---|---|
| https://access.redhat.com/security/cve/CVE-2024-38601 | 2024-09-24 | |
| https://bugzilla.redhat.com/show_bug.cgi?id=2293364 | 2024-09-24 |
Affected Vendors, Products, and Versions
| Vendor | Product | Version | Other | Status | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 4.19.316 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 4.19.316" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 5.4.278 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 5.4.278" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 5.10.219 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 5.10.219" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 5.15.161 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 5.15.161" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 6.1.93 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 6.1.93" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 6.6.33 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 6.6.33" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 6.8.12 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 6.8.12" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 6.9.3 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 6.9.3" | en |
Affected
| ||||||
| Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 3.5 < 6.10 Search vendor "Linux" for product "Linux Kernel" and version " >= 3.5 < 6.10" | en |
Affected
| ||||||