4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
[ Upstream commit 457ae7268b29c33dee1c0feb143a15f6029d177b ]
This isn't super serious because you need CAP_ADMIN to run this code.
I added this integer overflow check last year but apparently I am
rubbish at writing integer overflow checks... There are two issues.
First, access_ok() works on unsigned long type and not u64 so on 32 bit
systems the access_ok() could be checking a truncated size. The other
issue is that we should be using a stricter limit so we don't overflow
the kzalloc() setting ctx->clone_roots later in the function after the
access_ok():
alloc_size = sizeof(struct clone_root) * (arg->clone_sources_count + 1);
sctx->clone_roots = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN);
Fixes: f5ecec3ce21f ("btrfs: send: silence an integer overflow warning")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
[ added comment ]
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/btrfs/send.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -6196,8 +6196,13 @@ long btrfs_ioctl_send(struct file *mnt_f
goto out;
}
+ /*
+ * Check that we don't overflow at later allocations, we request
+ * clone_sources_count + 1 items, and compare to unsigned long inside
+ * access_ok.
+ */
if (arg->clone_sources_count >
- ULLONG_MAX / sizeof(*arg->clone_sources)) {
+ ULONG_MAX / sizeof(struct clone_root) - 1) {
ret = -EINVAL;
goto out;
}