From: Eric Biggers ebiggers@google.com Subject: fs/minix: check return value of sb_getblk()
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.
Link: http://lkml.kernel.org/r/20200628060846.682158-1-ebiggers@kernel.org Link: http://lkml.kernel.org/r/20200628060846.682158-2-ebiggers@kernel.org Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Eric Biggers ebiggers@google.com Reported-by: syzbot+4a88b2b9dc280f47baf4@syzkaller.appspotmail.com Cc: Qiujun Huang anenbupt@gmail.com Cc: Alexander Viro viro@zeniv.linux.org.uk Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
fs/minix/itree_common.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
--- a/fs/minix/itree_common.c~fs-minix-check-return-value-of-sb_getblk +++ a/fs/minix/itree_common.c @@ -75,6 +75,7 @@ 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++) { @@ -85,6 +86,11 @@ 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; @@ -103,7 +109,7 @@ 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, _