From: Eric Biggers <ebiggers@xxxxxxxxxx>
sb_getblk() can fail, so check its return value.
This fixes a NULL pointer dereference.
Reported-by: syzbot+4a88b2b9dc280f47baf4@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@xxxxxxxxxxxxxxx
Originally-from: Qiujun Huang <anenbupt@xxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
---
fs/minix/itree_common.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/fs/minix/itree_common.c b/fs/minix/itree_common.c
index 043c3fdbc8e7..446148792f41 100644
--- a/fs/minix/itree_common.c
+++ b/fs/minix/itree_common.c
@@ -75,6 +75,7 @@ static int alloc_branch(struct inode *inode,
int n = 0;
int i;
int parent = minix_new_block(inode);
+ int err = -ENOSPC;
branch[0].key = cpu_to_block(parent);
if (parent) for (n = 1; n < num; n++) {
@@ -85,6 +86,11 @@ static int alloc_branch(struct inode *inode,
break;
branch[n].key = cpu_to_block(nr);
bh = sb_getblk(inode->i_sb, parent);
+ if (!bh) {
+ minix_free_block(inode, nr);
+ err = -ENOMEM;
+ break;
+ }
lock_buffer(bh);
memset(bh->b_data, 0, bh->b_size);
branch[n].bh = bh;
@@ -103,7 +109,7 @@ static int alloc_branch(struct inode *inode,
bforget(branch[i].bh);
for (i = 0; i < n; i++)
minix_free_block(inode, block_to_cpu(branch[i].key));
- return -ENOSPC;
+ return err;
}
static inline int splice_branch(struct inode *inode,
--
2.27.0
