[PATCH AUTOSEL 5.4 3/3] locks: fix KASAN: use-after-free in trace_event_raw_event_filelock_lock

Sasha Levin
2023-09-07T16:13:52Z

From: Will Shiu <Will.Shiu@mediatek.com>

[ Upstream commit 74f6f5912693ce454384eaeec48705646a21c74f ]

As following backtrace, the struct file_lock request , in posix_lock_inode
is free before ftrace function using.
Replace the ftrace function ahead free flow could fix the use-after-free
issue.

[name:report&]===============================================
BUG:KASAN: use-after-free in trace_event_raw_event_filelock_lock+0x80/0x12c
[name:report&]Read at addr f6ffff8025622620 by task NativeThread/16753
[name:report_hw_tags&]Pointer tag: [f6], memory tag: [fe]
[name:report&]
BT:
Hardware name: MT6897 (DT)
Call trace:
dump_backtrace+0xf8/0x148
show_stack+0x18/0x24
dump_stack_lvl+0x60/0x7c
print_report+0x2c8/0xa08
kasan_report+0xb0/0x120
__do_kernel_fault+0xc8/0x248
do_bad_area+0x30/0xdc
do_tag_check_fault+0x1c/0x30
do_mem_abort+0x58/0xbc
el1_abort+0x3c/0x5c
el1h_64_sync_handler+0x54/0x90
el1h_64_sync+0x68/0x6c
trace_event_raw_event_filelock_lock+0x80/0x12c
posix_lock_inode+0xd0c/0xd60
do_lock_file_wait+0xb8/0x190
fcntl_setlk+0x2d8/0x440
...
[name:report&]
[name:report&]Allocated by task 16752:
...
slab_post_alloc_hook+0x74/0x340
kmem_cache_alloc+0x1b0/0x2f0
posix_lock_inode+0xb0/0xd60
...
[name:report&]
[name:report&]Freed by task 16752:
...
kmem_cache_free+0x274/0x5b0
locks_dispose_list+0x3c/0x148
posix_lock_inode+0xc40/0xd60
do_lock_file_wait+0xb8/0x190
fcntl_setlk+0x2d8/0x440
do_fcntl+0x150/0xc18
...

Signed-off-by: Will Shiu <Will.Shiu@mediatek.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/locks.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/locks.c b/fs/locks.c
index b8a31c1c4fff3..90f92784aa554 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1338,6 +1338,7 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
out:
spin_unlock(&ctx->flc_lock);
percpu_up_read(&file_rwsem);
+ trace_posix_lock_inode(inode, request, error);
/*
* Free any unused locks.
*/
@@ -1346,7 +1347,6 @@ static int posix_lock_inode(struct inode *inode, struct file_lock *request,
if (new_fl2)
locks_free_lock(new_fl2);
locks_dispose_list(&dispose);
- trace_posix_lock_inode(inode, request, error);

return error;
}
--
2.40.1