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CVE-2023-52786

ext4: fix racy may inline data check in dio write PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 310ee0902b8d9d0a13a5a13e94688a5863fa29c2 before e3b83d87c93eb6fc96a80b5e8527f7dc9f5a11bc; affected 310ee0902b8d9d0a13a5a13e94688a5863fa29c2 before 7343c23ebcadbedc23a7063d1e24d976eccb0d0d; affected 310ee0902b8d9d0a13a5a13e94688a5863fa29c2 before ce56d21355cd6f6937aca32f1f44ca749d1e4808
Linux / Linuxaffected 6.5; unaffected 0 before 6.5; unaffected 6.5.13 through 6.5.*; unaffected 6.6.3 through 6.6.*; unaffected 6.7 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

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CVE

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