Описание
In the Linux kernel, the following vulnerability has been resolved: ubifs: ubifs_releasepage: Remove ubifs_assert(0) to valid this process There are two states for ubifs writing pages:
- Dirty, Private
- Not Dirty, Not Private
The normal process cannot go to ubifs_releasepage() which means there
exists pages being private but not dirty. Reproducer[1] shows that it
could occur (which maybe related to [2]) with following process:
PA PB PC
lock(page)[PA]
ubifs_write_end
attach_page_private // set Private
__set_page_dirty_nobuffers // set Dirty
unlock(page)
write_cache_pages[PA]
lock(page)
clear_page_dirty_for_io(page)// clear Dirty
ubifs_writepage
do_truncation[PB]
truncate_setsize
i_size_write(inode, newsize) // newsize = 0
i_size = i_size_read(inode)// i_size = 0
end_index = i_size >> PAGE_SHIFT
if (page->index > end_index)
goto out // jump
out:
unlock(page) // Private, Not Dirty
generic_fadvise[PC]
lock(page)
invalidate_inode_page
try_to_release_page
ubifs_releasepage
ubifs_assert(c, 0)
// bad assertion!
unlock(page)
truncate_pagecache[PB]
Then we may get following assertion failed:
UBIFS error (ubi0:0 pid 1683): ubifs_assert_failed [ubifs]:
UBIFS assert failed: 0, in fs/ubifs/file.c:1513
UBIFS warning (ubi0:0 pid 1683): ubifs_ro_mode [ubifs]:
switched to read-only mode, error -22
CPU: 2 PID: 1683 Comm: aa Not tainted 5.16.0-rc5-00184-g0bca5994cacc-dirty #308
Call Trace:
dump_stack+0x13/0x1b
ubifs_ro_mode+0x54/0x60 [ubifs]
ubifs_assert_failed+0x4b/0x80 [ubifs]
ubifs_releasepage+0x67/0x1d0 [ubifs]
try_to_release_page+0x57/0xe0
invalidate_inode_page+0xfb/0x130
__invalidate_mapping_pages+0xb9/0x280
invalidate_mapping_pagevec+0x12/0x20
generic_fadvise+0x303/0x3c0
ksys_fadvise64_64+0x4c/0xb0
[1] https://bugzilla.kernel.org/show_bug.cgi?id=215373
[2] https://linux-mtd.infradead.narkive.com/NQoBeT1u/patch-rfc-ubifs-fix-assert-failed-in-ubifs-set-page-dirty
A race condition was found in the Linux kernel's UBIFS filesystem in the page release logic. A local user can trigger this issue through concurrent file operations including writes, truncation, and cache invalidation, causing pages to become private but not dirty due to timing of dirty flag clearing and size updates. This results in hitting an assertion in ubifs_releasepage when the filesystem attempts to release pages in an unexpected state, leading to filesystem errors and denial of service.
Отчет
The race occurs across three concurrent operations: Process A writes and dirties a page with UBIFS private data, then clears the dirty flag during writeback. Process B truncates the file to zero size. Process A checks the new file size, finds the page is now beyond EOF, and unlocks it without finishing writeback—leaving it private but not dirty. Process C then calls fadvise which attempts to invalidate the page, calling ubifs_releasepage on a private, non-dirty page. This state violates the driver's assumption that private pages are always dirty, triggering an assertion that switches the filesystem to read-only mode. The race window requires precise timing between write, truncate, and fadvise operations, but can occur during normal concurrent filesystem use.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Not affected | ||
| Red Hat Enterprise Linux 6 | kernel | Out of support scope | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Not affected |
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Дополнительная информация
Статус:
EPSS
5.5 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: ubifs: ubifs_releasepage: Remove ubifs_assert(0) to valid this process There are two states for ubifs writing pages: 1. Dirty, Private 2. Not Dirty, Not Private The normal process cannot go to ubifs_releasepage() which means there exists pages being private but not dirty. Reproducer[1] shows that it could occur (which maybe related to [2]) with following process: PA PB PC lock(page)[PA] ubifs_write_end attach_page_private // set Private __set_page_dirty_nobuffers // set Dirty unlock(page) write_cache_pages[PA] lock(page) clear_page_dirty_for_io(page) // clear Dirty ubifs_writepage do_truncation[PB] truncate_setsize i_size_write(inode, newsize) // newsize = 0 i_size = i_size_read(inode) // i_size = 0 end_index = i_size >> PAGE_SHIFT if (page->index > end_index) goto out // jump out: unlock(page) // Private, Not Dirty generic_fadvise[PC] lock(page) invalidate_inode_pag...
In the Linux kernel, the following vulnerability has been resolved: ubifs: ubifs_releasepage: Remove ubifs_assert(0) to valid this process There are two states for ubifs writing pages: 1. Dirty, Private 2. Not Dirty, Not Private The normal process cannot go to ubifs_releasepage() which means there exists pages being private but not dirty. Reproducer[1] shows that it could occur (which maybe related to [2]) with following process: PA PB PC lock(page)[PA] ubifs_write_end attach_page_private // set Private __set_page_dirty_nobuffers // set Dirty unlock(page) write_cache_pages[PA] lock(page) clear_page_dirty_for_io(page) // clear Dirty ubifs_writepage do_truncation[PB] truncate_setsize i_size_write(inode, newsize) // newsize = 0 i_size = i_size_read(inode) // i_size = 0 end_index = i_size >> PAGE_SHIFT if (page->index > end_index) goto out // jump out: unlock(page)
In the Linux kernel, the following vulnerability has been resolved: u ...
In the Linux kernel, the following vulnerability has been resolved: ubifs: ubifs_releasepage: Remove ubifs_assert(0) to valid this process There are two states for ubifs writing pages: 1. Dirty, Private 2. Not Dirty, Not Private The normal process cannot go to ubifs_releasepage() which means there exists pages being private but not dirty. Reproducer[1] shows that it could occur (which maybe related to [2]) with following process: PA PB PC lock(page)[PA] ubifs_write_end attach_page_private // set Private __set_page_dirty_nobuffers // set Dirty unlock(page) write_cache_pages[PA] lock(page) clear_page_dirty_for_io(page) // clear Dirty ubifs_writepage do_truncation[PB] truncate_setsize i_size_write(inode, newsize) // newsize = 0 i_size = i_size_read(inode) // i_size = 0 end_index = i_size >> PAGE_SHIFT if (page->index > end_index) goto out // jump out: unlock(page)...
EPSS
5.5 Medium
CVSS3