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authorMarc Dionne <marc.dionne@auristor.com>2019-08-22 13:28:43 +0100
committerDavid Howells <dhowells@redhat.com>2019-08-22 13:33:26 +0100
commitc4c613ff08d92e72bf64a65ec35a2c3aa1cfcd06 (patch)
tree2e5b2adfec2f534597e52aaa407802a438168ab8
parenta5fb8e6c02d6a518fb2b1a2b8c2471fa77b69436 (diff)
downloadlinux-c4c613ff08d92e72bf64a65ec35a2c3aa1cfcd06.tar.bz2
afs: Fix possible oops in afs_lookup trace event
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>
-rw-r--r--fs/afs/dir.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 81207dc3c997..139b4e3cc946 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -959,7 +959,8 @@ 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;
}