From a0e25f0a0d39d66c048d5dbac1e7ebaa6ec885d7 Mon Sep 17 00:00:00 2001 From: Dave Wysochanski Date: Sun, 3 Oct 2021 12:14:00 -0400 Subject: cachefiles: Fix oops with cachefiles_cull() due to NULL object When cachefiles_cull() calls cachefiles_bury_object(), it passes a NULL object. When this occurs, either trace_cachefiles_unlink() or trace_cachefiles_rename() may oops due to the NULL object. Check for NULL object in the tracepoint and if so, set debug_id to MAX_UINT as was done in 2908f5e101e3. The following oops was seen with xfstests generic/100. BUG: kernel NULL pointer dereference, address: 0000000000000010 ... RIP: 0010:trace_event_raw_event_cachefiles_unlink+0x4e/0xa0 [cachefiles] ... Call Trace: cachefiles_bury_object+0x242/0x430 [cachefiles] ? __vfs_removexattr_locked+0x10f/0x150 ? vfs_removexattr+0x51/0xd0 cachefiles_cull+0x84/0x120 [cachefiles] cachefiles_daemon_cull+0xd1/0x120 [cachefiles] cachefiles_daemon_write+0x158/0x190 [cachefiles] vfs_write+0xbc/0x260 ksys_write+0x4f/0xc0 do_syscall_64+0x3b/0x90 The following oops was seen with xfstests generic/290. BUG: kernel NULL pointer dereference, address: 0000000000000010 ... RIP: 0010:trace_event_raw_event_cachefiles_rename+0x54/0xa0 [cachefiles] ... Call Trace: cachefiles_bury_object+0x35c/0x430 [cachefiles] cachefiles_cull+0x84/0x120 [cachefiles] cachefiles_daemon_cull+0xd1/0x120 [cachefiles] cachefiles_daemon_write+0x158/0x190 [cachefiles] vfs_write+0xbc/0x260 ksys_write+0x4f/0xc0 do_syscall_64+0x3b/0x90 Fixes: 2908f5e101e3 ("fscache: Add a cookie debug ID and use that in traces") Signed-off-by: Dave Wysochanski Signed-off-by: David Howells Link: https://listman.redhat.com/archives/linux-cachefs/2021-October/msg00009.html --- include/trace/events/cachefiles.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/include/trace/events/cachefiles.h b/include/trace/events/cachefiles.h index 695bfdbfdcad..920b6a303d60 100644 --- a/include/trace/events/cachefiles.h +++ b/include/trace/events/cachefiles.h @@ -178,7 +178,7 @@ TRACE_EVENT(cachefiles_unlink, ), TP_fast_assign( - __entry->obj = obj->fscache.debug_id; + __entry->obj = obj ? obj->fscache.debug_id : UINT_MAX; __entry->de = de; __entry->why = why; ), @@ -205,7 +205,7 @@ TRACE_EVENT(cachefiles_rename, ), TP_fast_assign( - __entry->obj = obj->fscache.debug_id; + __entry->obj = obj ? obj->fscache.debug_id : UINT_MAX; __entry->de = de; __entry->to = to; __entry->why = why; -- cgit