[ Upstream commit c4c613ff08d92e72bf64a65ec35a2c3aa1cfcd06 ]
The afs_lookup trace event can cause the following:
[ 216.576777] BUG: kernel NULL pointer dereference, address: 000000000000023b [ 216.576803] #PF: supervisor read access in kernel mode [ 216.576813] #PF: error_code(0x0000) - not-present page ... [ 216.576913] RIP: 0010:trace_event_raw_event_afs_lookup+0x9e/0x1c0 [kafs]
If the inode from afs_do_lookup() is an error other than ENOENT, or if it is ENOENT and afs_try_auto_mntpt() returns an error, the trace event will try to dereference the error pointer as a valid pointer.
Use IS_ERR_OR_NULL to only pass a valid pointer for the trace, or NULL.
Ideally the trace would include the error value, but for now just avoid the oops.
Fixes: 80548b03991f ("afs: Add more tracepoints") Signed-off-by: Marc Dionne marc.dionne@auristor.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/afs/dir.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 9620f19308f58..9bd5c067d55d1 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -960,7 +960,8 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, inode ? AFS_FS_I(inode) : NULL); } else { trace_afs_lookup(dvnode, &dentry->d_name, - inode ? AFS_FS_I(inode) : NULL); + IS_ERR_OR_NULL(inode) ? NULL + : AFS_FS_I(inode)); } return d; }