CVE-2023-52786: linux kernel — Fix

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.

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CVSS v3.1 Score

4.7

MEDIUM

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-667 CWE-667

Affected Products

Vendor	Product	Versions
linux	linux_kernel	6.5 — 6.5.13
linux	linux_kernel	6.6 — 6.6.3

References

Advisories & Patches

https://git.kernel.org/stable/c/7343c23ebcadbedc23a7063d1e24d976eccb0d0d https://git.kernel.org/stable/c/ce56d21355cd6f6937aca32f1f44ca749d1e4808 https://git.kernel.org/stable/c/e3b83d87c93eb6fc96a80b5e8527f7dc9f5a11bc https://git.kernel.org/stable/c/7343c23ebcadbedc23a7063d1e24d976eccb0d0d https://git.kernel.org/stable/c/ce56d21355cd6f6937aca32f1f44ca749d1e4808 https://git.kernel.org/stable/c/e3b83d87c93eb6fc96a80b5e8527f7dc9f5a11bc

Frequently Asked Questions

What is CVE-2023-52786? +

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. It has a CVSS v3.1 base score of 4.7 (MEDIUM).

How severe is CVE-2023-52786? +

CVE-2023-52786 has a CVSS v3.1 score of 4.7 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2023-52786? +

CVE-2023-52786 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2023-52786? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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