This is a note to let you know that I've just added the patch titled bfs: add sanity check at bfs_fill_super() to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: bfs-add-sanity-check-at-bfs_fill_super.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 9f2df09a33aa2c76ce6385d382693f98d7f2f07e Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Date: Fri, 2 Nov 2018 15:48:42 -0700 Subject: bfs: add sanity check at bfs_fill_super() From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> commit 9f2df09a33aa2c76ce6385d382693f98d7f2f07e upstream. syzbot is reporting too large memory allocation at bfs_fill_super() [1]. Since file system image is corrupted such that bfs_sb->s_start == 0, bfs_fill_super() is trying to allocate 8MB of continuous memory. Fix this by adding a sanity check on bfs_sb->s_start, __GFP_NOWARN and printf(). [1] https://syzkaller.appspot.com/bug?id=16a87c236b951351374a84c8a32f40edbc034e96 Link: http://lkml.kernel.org/r/1525862104-3407-1-git-send-email-penguin-kernel@xxxxxxxxxxxxxxxxxxx Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Reported-by: syzbot <syzbot+71c6b5d68e91149fc8a4@xxxxxxxxxxxxxxxxxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Tigran Aivazian <aivazian.tigran@xxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/bfs/inode.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/fs/bfs/inode.c +++ b/fs/bfs/inode.c @@ -350,7 +350,8 @@ static int bfs_fill_super(struct super_b s->s_magic = BFS_MAGIC; - if (le32_to_cpu(bfs_sb->s_start) > le32_to_cpu(bfs_sb->s_end)) { + if (le32_to_cpu(bfs_sb->s_start) > le32_to_cpu(bfs_sb->s_end) || + le32_to_cpu(bfs_sb->s_start) < BFS_BSIZE) { printf("Superblock is corrupted\n"); goto out1; } @@ -359,9 +360,11 @@ static int bfs_fill_super(struct super_b sizeof(struct bfs_inode) + BFS_ROOT_INO - 1; imap_len = (info->si_lasti / 8) + 1; - info->si_imap = kzalloc(imap_len, GFP_KERNEL); - if (!info->si_imap) + info->si_imap = kzalloc(imap_len, GFP_KERNEL | __GFP_NOWARN); + if (!info->si_imap) { + printf("Cannot allocate %u bytes\n", imap_len); goto out1; + } for (i = 0; i < BFS_ROOT_INO; i++) set_bit(i, info->si_imap); Patches currently in stable-queue which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are queue-4.9/bfs-add-sanity-check-at-bfs_fill_super.patch queue-4.9/selinux-add-__gfp_nowarn-to-allocation-at-str_read.patch