dm-integrity: Avoid divide by zero in table status in Inline mode

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: dm-integrity: Avoid divide by zero in table status in Inline mode In Inline mode, the journal is unused, and journal_sectors is zero. Calculating the journal watermark requires dividing by journal_sectors, which should be done only if the journal is configured. Otherwise, a simple table query (dmsetup table) can cause OOPS. This bug did not show on some systems, perhaps only due to compiler optimization. On my 32-bit testing machine, this reliably crashes with the following: : Oops: divide error: 0000 [#1] PREEMPT SMP : CPU: 0 UID: 0 PID: 2450 Comm: dmsetup Not tainted 6.14.0-rc2+ #959 : EIP: dm_integrity_status+0x2f8/0xab0 [dm_integrity] ...

References

• https://git.kernel.org/stable/c/22c6f577b3cb184857b440ae5e5916f6c9e7021d
• https://git.kernel.org/stable/c/06d9895f265282e939a8933bb18de82eba2b4dda
• https://git.kernel.org/stable/c/7fb39882b20c98a9a393c244c86b56ef6933cff8