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CVE PROGRAM SOURCE RECORDUnscored

CVE-2022-49171

ext4: don't BUG if someone dirty pages without asking ext4 first

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: don't BUG if someone dirty pages without asking ext4 first [un]pin_user_pages_remote is dirtying pages without properly warning the file system in advance. A related race was noted by Jan Kara in 2018[1]; however, more recently instead of it being a very hard-to-hit race, it could be reliably triggered by process_vm_writev(2) which was discovered by Syzbot[2]. This is technically a bug in mm/gup.c, but arguably ext4 is fragile in that if some other kernel subsystem dirty pages without properly notifying the file system using page_mkwrite(), ext4 will BUG, while other file systems will not BUG (although data will still be lost). So instead of crashing with a BUG, issue a warning (since there may be potential data loss) and just mark the page as clean to avoid unprivileged denial of service attacks until the problem can be properly fixed. More discussion and background can be found in the thread starting at [2]. [1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz [2] https://lore.kernel.org/r/Yg0m6IjcNmfaSokM@google.com

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < 5db60e76edf5680ff1f3a7221036fc44b308f146affected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < d666dfaa571465a19f014534a214c255ea33f301affected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < 0d3a6926f7e8be3c897fa46216ce13b119a9f56aaffected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < 5a016c053f426a73752c3b41b60b497b58694d48affected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < 330d0e44fc5a47c27df958ecdd4693a3cb1d8b81affected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < a0856764dc1276ad2dc7891288c2e9246bf11a37affected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < 343117559ef41e992e326f7a92da1a8f254dfa8caffected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < 677c9d30e8487bee6c8e3b034070319d98f6e203affected
  • a42afc5f56f319107e987aa6adf2f65d93d527c7 to < cc5095747edfb054ca2068d01af20be3fcc3634faffected

Linux Linux

Default version status: affected

  • 2.6.37affected
  • 0 to < 2.6.37unaffected
  • 4.9.311 to ≤ 4.9.*unaffected
  • 4.14.276 to ≤ 4.14.*unaffected
  • 4.19.238 to ≤ 4.19.*unaffected
  • 5.4.189 to ≤ 5.4.*unaffected
  • 5.10.110 to ≤ 5.10.*unaffected
  • 5.15.33 to ≤ 5.15.*unaffected
  • 5.16.19 to ≤ 5.16.*unaffected
  • 5.17.2 to ≤ 5.17.*unaffected
  • 5.18 to ≤ *unaffected

References