[PATCH v3] fs/exfat: resolve memory leak from exfat_create_upcase_table()

From: Daniel Yang
Date: Mon Sep 16 2024 - 19:05:25 EST


If exfat_load_upcase_table reaches end and returns -EINVAL,
allocated memory doesn't get freed and while
exfat_load_default_upcase_table allocates more memory, leading to a
memory leak.

Here's link to syzkaller crash report illustrating this issue:
https://syzkaller.appspot.com/text?tag=CrashReport&x=1406c201980000

Signed-off-by: Daniel Yang <danielyangkang@xxxxxxxxx>
Reported-by: syzbot+e1c69cadec0f1a078e3d@xxxxxxxxxxxxxxxxxxxxxxxxx
---
V2 -> V3: free(NULL) is no-op, removed if() check
V1 -> V2: Moved the mem free to create_upcase_table

fs/exfat/nls.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c
index afdf13c34..1ac011088 100644
--- a/fs/exfat/nls.c
+++ b/fs/exfat/nls.c
@@ -779,8 +779,11 @@ int exfat_create_upcase_table(struct super_block *sb)
le32_to_cpu(ep->dentry.upcase.checksum));

brelse(bh);
- if (ret && ret != -EIO)
+ if (ret && ret != -EIO) {
+ /* free memory from exfat_load_upcase_table call */
+ exfat_free_upcase_table(sbi);
goto load_default;
+ }

/* load successfully */
return ret;
--
2.39.2