Created attachment 290699 [details]
KASAN report a use-after-free bug when the alloc_workqueue() return NULL in the following call stack:
1. alloc_workqueue(xfs_log.c, 1480)
2. xlog_alloc_log(xfs_log.c, 599)
3. xfs_log_mount(xfs_mount.c, 811)
4. xfs_mountfs(xfs_super.c, 1732)
6. mount_bdev(xfs_super.c, 1806)
When alloc_workqueue() returns NULL, the kernel thread enter the error handling code entrance out_free_iclog. In out_free_iclog, the thread frees log->l_iclog in a for loop. However, log->l_iclog is a ring. When all iclogs have been freed, The for loop will come to the ring head and free the iclogs again.
The Linux kernel crashes.
You've reported this on a 5.4.0 kernel from November 2019 (please, in future bug reports include the kernel version more prominently)
Author: Brian Foster <firstname.lastname@example.org>
Date: Tue Dec 3 07:53:15 2019 -0800
xfs: fix mount failure crash on invalid iclog memory access
syzbot (via KASAN) reports a use-after-free in the error path of
xlog_alloc_log(). Specifically, the iclog freeing loop doesn't
handle the case of a fully initialized ->l_iclog linked list.
Instead, it assumes that the list is partially constructed and NULL
This bug manifested because there was no possible error scenario
after iclog list setup when the original code was added. Subsequent
code and associated error conditions were added some time later,
while the original error handling code was never updated. Fix up the
error loop to terminate either on a NULL iclog or reaching the end
of the list.
Signed-off-by: Brian Foster <email@example.com>
Reviewed-by: Darrick J. Wong <firstname.lastname@example.org>
Signed-off-by: Darrick J. Wong <email@example.com>
went into v5.5
I believe this is already resolved; if you have a reproducer can you please test? If you believe this bug is still not fixed, please re-open this bug.