From: Eric Biggers <ebiggers@xxxxxxxxxx>
commit da27e0a0e5f655f0d58d4e153c3182bb2b290f64 upstream.
Patch series "fs/minix: fix syzbot bugs and set s_maxbytes".
This series fixes all syzbot bugs in the minix filesystem:
KASAN: null-ptr-deref Write in get_block
KASAN: use-after-free Write in get_block
KASAN: use-after-free Read in get_block
WARNING in inc_nlink
KMSAN: uninit-value in get_block
WARNING in drop_nlink
It also fixes the minix filesystem to set s_maxbytes correctly, so that
userspace sees the correct behavior when exceeding the max file size.
This patch (of 6):
sb_getblk() can fail, so check its return value.
This fixes a NULL pointer dereference.
Originally from Qiujun Huang.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+4a88b2b9dc280f47baf4@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Qiujun Huang <anenbupt@xxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/20200628060846.682158-1-ebiggers@xxxxxxxxxx
Link: http://lkml.kernel.org/r/20200628060846.682158-2-ebiggers@xxxxxxxxxx
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/minix/itree_common.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
--- a/fs/minix/itree_common.c
+++ b/fs/minix/itree_common.c
@@ -74,6 +74,7 @@ static int alloc_branch(struct inode *in
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++) {
@@ -84,6 +85,11 @@ static int alloc_branch(struct inode *in
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;
@@ -102,7 +108,7 @@ static int alloc_branch(struct inode *in
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,
