On Fri, Jan 12, 2024 at 07:50:07PM +0300, Mikhail Ukhin wrote: > Fuzzing of 5.10 stable branch shows NULL pointer dereference happens in > lbmStartIO() on log->bdev pointer. The reason for bdev being NULL is the > JFS_NOINTEGRITY flag is set on mount of this fs. When this flag is enabled, > it results in the open_dummy_log function being called, which initializes a > new dummy_log, but does not assign a value to bdev. > > The error is fixed in 5.18 by commit > 07888c665b405b1cd3577ddebfeb74f4717a84c4. > Backport of this commit is too intrusive, so it is more reasonable to apply > a small patch to fix this issue. > > Found by Linux Verification Center (linuxtesting.org) with syzkaller. > > Signed-off-by: Mikhail Ukhin <mish.uxin2012@xxxxxxxxx> > Signed-off-by: Mikhail Ivanov <iwanov-23@xxxxx> > Signed-off-by: Pavel Koshutin <koshutin.pavel@xxxxxxxxx> > Signed-off-by: Artem Sadovnikov <ancowi69@xxxxxxxxx> > --- > fs/jfs/jfs_logmgr.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) Who is using jfs in 5.10 and 5.15? Why not just mark the filesystem as BROKEN there instead? If you need to access your ancient filesystem image just use a newer kernel. For filesystems that are not used in older kernels, work like this feels odd, especially for something just like a NULL dereference which doesn't do much, right? thanks, greg k-h
