We need to take reference to the s_li_request after we take a mutex,
because it might be freed since then, hence result in accessing old
already freed memory. Also we should protect the whole
ext4_remove_li_request() because ext4_li_info might be in the process of
being freed in ext4_lazyinit_thread().
Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
---
fs/ext4/super.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c379af6..6a8e48f 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2721,14 +2721,16 @@ static void ext4_remove_li_request(struct ext4_li_request *elr)
static void ext4_unregister_li_request(struct super_block *sb)
{
- struct ext4_li_request *elr = EXT4_SB(sb)->s_li_request;
-
- if (!ext4_li_info)
+ mutex_lock(&ext4_li_mtx);
+ if (!ext4_li_info) {
+ mutex_unlock(&ext4_li_mtx);
return;
+ }
mutex_lock(&ext4_li_info->li_list_mtx);
- ext4_remove_li_request(elr);
+ ext4_remove_li_request(EXT4_SB(sb)->s_li_request);
mutex_unlock(&ext4_li_info->li_list_mtx);
+ mutex_unlock(&ext4_li_mtx);
}
static struct task_struct *ext4_lazyinit_task;
--
1.7.4.4
--
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