CVE-2023-52786

ext4: fix racy may inline data check in dio write

Published May 21, 2024 CVSS 3.1 · 4.7 Medium EPSS < 1% KEV · Not listed
Description
In the Linux kernel, the following vulnerability has been resolved:

ext4: fix racy may inline data check in dio write

syzbot reports that the following warning from ext4_iomap_begin()
triggers as of the commit referenced below:

if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
return -ERANGE;

This occurs during a dio write, which is never expected to encounter
an inode with inline data. To enforce this behavior,
ext4_dio_write_iter() checks the current inline state of the inode
and clears the MAY_INLINE_DATA state flag to either fall back to
buffered writes, or enforce that any other writers in progress on
the inode are not allowed to create inline data.

The problem is that the check for existing inline data and the state
flag can span a lock cycle. For example, if the ilock is originally
locked shared and subsequently upgraded to exclusive, another writer
may have reacquired the lock and created inline data before the dio
write task acquires the lock and proceeds.

The commit referenced below loosens the lock requirements to allow
some forms of unaligned dio writes to occur under shared lock, but
AFAICT the inline data check was technically already racy for any
dio write that would have involved a lock cycle. Regardless, lift
clearing of the state bit to the same lock critical section that
checks for preexisting inline data on the inode to close the race.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Weaknesses CWE-667
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
May 11, 2026, 7:33 PM
Reserved
May 21, 2024, 3:19 PM
Status
Analyzed
Published
May 21, 2024, 4:15 PM
Modified
Jun 17, 2026, 6:43 AM
Severity
Moderate
Public date
May 21, 2024, 12:00 AM