Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix bounds check in check_xattrs() to prevent out-of-bounds access The bounds check for the next xattr entry in check_xattrs() uses (void *)next >= end, which allows next to point within sizeof(u32) bytes of end. On the next loop iteration, IS_LAST_ENTRY() reads 4 bytes via *(__u32 *)(entry), which can overrun the valid xattr region. For example, if next lands at end - 1, the check passes since next < end, but IS_LAST_ENTRY() reads 4 bytes starting at end - 1, accessing 3 bytes beyond the valid region. Fix this by changing the check to (void *)next + sizeof(u32) > end, ensuring there is always enough space for the IS_LAST_ENTRY() read on the subsequent iteration.

References 5

• git.kernel.org https://git.kernel.org/stable/c/520986722dbf869c122252123fc161c7302eab7d
• git.kernel.org https://git.kernel.org/stable/c/537e065977022aa22f2c2503e8accaf16622e0fd
• git.kernel.org https://git.kernel.org/stable/c/5a5314d2387633a272a04d1bd8727f99058e4e68
• git.kernel.org https://git.kernel.org/stable/c/ab6da97bc310db35d4e4ef5354bc3ff626b0698c
• git.kernel.org https://git.kernel.org/stable/c/eceafc31ea7b42c984ece10d79d505c0bb6615d5

Remediation