| Message ID | 20230528173546.593511-1-princekumarmaurya06@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | Null check to prevent null-ptr-deref bug | expand |
On Sun, May 28, 2023 at 10:35:46AM -0700, Prince Kumar Maurya wrote: > sb_getblk(inode->i_sb, parent) return a null ptr and taking lock on > that leads to the null-ptr-deref bug. > > Signed-off-by: Prince Kumar Maurya <princekumarmaurya06@gmail.com> > --- > Change since v1: update the commit message. Your subject: line needs to also be fixed up. Please see the kernel documentation for how to do this properly. thanks greg k-h
On Sun, May 28, 2023 at 10:35:46AM -0700, Prince Kumar Maurya wrote: > sb_getblk(inode->i_sb, parent) return a null ptr and taking lock on > that leads to the null-ptr-deref bug. > > Signed-off-by: Prince Kumar Maurya <princekumarmaurya06@gmail.com> > --- > Change since v1: update the commit message. > The bug was reproducible using the reproducer code and assets found in > bug report:https://syzkaller.appspot.com/bug?extid=aad58150cbc64ba41bdc Also, did you forget to properly credit the syzbot tool like it asks you to?
diff --git a/fs/sysv/itree.c b/fs/sysv/itree.c index b22764fe669c..3a6b66e719fd 100644 --- a/fs/sysv/itree.c +++ b/fs/sysv/itree.c @@ -145,6 +145,8 @@ static int alloc_branch(struct inode *inode, */ parent = block_to_cpu(SYSV_SB(inode->i_sb), branch[n-1].key); bh = sb_getblk(inode->i_sb, parent); + if (!bh) + break; lock_buffer(bh); memset(bh->b_data, 0, blocksize); branch[n].bh = bh;
sb_getblk(inode->i_sb, parent) return a null ptr and taking lock on that leads to the null-ptr-deref bug. Signed-off-by: Prince Kumar Maurya <princekumarmaurya06@gmail.com> --- Change since v1: update the commit message. The bug was reproducible using the reproducer code and assets found in bug report:https://syzkaller.appspot.com/bug?extid=aad58150cbc64ba41bdc I used qemu to reproduce the bug and after the code fix I rebooted the qemu with updated bzImage containing the fix. qemu-system-x86_64 -m 4G -nographic -drive \ file=./asset/disk-4d6d4c7f.raw,format=raw \ -enable-kvm -net nic -net user,hostfwd=tcp::2222-:22 fs/sysv/itree.c | 2 ++ 1 file changed, 2 insertions(+)