From: Filipe Manana fdmanana@suse.com
commit 1c78544eaa4660096aeb6a57ec82b42cdb3bfe5a upstream.
When faulting in the pages for the user supplied buffer for the search ioctl, we are passing only the base address of the buffer to the function fault_in_pages_writeable(). This means that after the first iteration of the while loop that searches for leaves, when we have a non-zero offset, stored in 'sk_offset', we try to fault in a wrong page range.
So fix this by adding the offset in 'sk_offset' to the base address of the user supplied buffer when calling fault_in_pages_writeable().
Several users have reported that the applications compsize and bees have started to operate incorrectly since commit a48b73eca4ceb9 ("btrfs: fix potential deadlock in the search ioctl") was added to stable trees, and these applications make heavy use of the search ioctls. This fixes their issues.
Link: https://lore.kernel.org/linux-btrfs/632b888d-a3c3-b085-cdf5-f9bb61017d92@lec... Link: https://github.com/kilobyte/compsize/issues/34 Fixes: a48b73eca4ceb9 ("btrfs: fix potential deadlock in the search ioctl") CC: stable@vger.kernel.org # 4.4+ Tested-by: A L mail@lechevalier.se Reviewed-by: Josef Bacik josef@toxicpanda.com Signed-off-by: Filipe Manana fdmanana@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/ioctl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2193,7 +2193,8 @@ static noinline int search_ioctl(struct key.offset = sk->min_offset;
while (1) { - ret = fault_in_pages_writeable(ubuf, *buf_size - sk_offset); + ret = fault_in_pages_writeable(ubuf + sk_offset, + *buf_size - sk_offset); if (ret) break;