[1/6] fs/minix: check return value of sb_getblk()
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Message ID 20200628060846.682158-2-ebiggers@kernel.org
State New
Headers show
Series
  • fs/minix: fix syzbot bugs and set s_maxbytes
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Commit Message

Eric Biggers June 28, 2020, 6:08 a.m. UTC
From: Eric Biggers <ebiggers@google.com>

sb_getblk() can fail, so check its return value.

This fixes a NULL pointer dereference.

Reported-by: syzbot+4a88b2b9dc280f47baf4@syzkaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Originally-from: Qiujun Huang <anenbupt@gmail.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 fs/minix/itree_common.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Andrew Morton July 7, 2020, 7:26 p.m. UTC | #1
On Sat, 27 Jun 2020 23:08:40 -0700 Eric Biggers <ebiggers@kernel.org> wrote:

> From: Eric Biggers <ebiggers@google.com>
> 
> sb_getblk() can fail, so check its return value.
> 
> This fixes a NULL pointer dereference.
> 
> Reported-by: syzbot+4a88b2b9dc280f47baf4@syzkaller.appspotmail.com
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable@vger.kernel.org
> Originally-from: Qiujun Huang <anenbupt@gmail.com>

Originally-from: isn't really a thing.  Did the original come with a
signed-off-by:?

> Signed-off-by: Eric Biggers <ebiggers@google.com>
>
> ...
>
Eric Biggers July 7, 2020, 8:34 p.m. UTC | #2
On Tue, Jul 07, 2020 at 12:26:12PM -0700, Andrew Morton wrote:
> On Sat, 27 Jun 2020 23:08:40 -0700 Eric Biggers <ebiggers@kernel.org> wrote:
> 
> > From: Eric Biggers <ebiggers@google.com>
> > 
> > sb_getblk() can fail, so check its return value.
> > 
> > This fixes a NULL pointer dereference.
> > 
> > Reported-by: syzbot+4a88b2b9dc280f47baf4@syzkaller.appspotmail.com
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Cc: stable@vger.kernel.org
> > Originally-from: Qiujun Huang <anenbupt@gmail.com>
> 
> Originally-from: isn't really a thing.  Did the original come with a
> signed-off-by:?
> 

Yes it did.  Qiujun's patch was
https://lkml.kernel.org/lkml/20200323125700.7512-1-hqjagain@gmail.com
But I basically started from scratch anyway and my patch ended up different,
so I didn't leave the original "Author:".  Feel free to adjust the patch.

- Eric

Patch
diff mbox series

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,