From: Dan Carpenter dan.carpenter@oracle.com
[ 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@oracle.com Reviewed-by: David Sterba dsterba@suse.com [ added comment ] Signed-off-by: David Sterba dsterba@suse.com
Signed-off-by: Sasha Levin alexander.levin@verizon.com --- fs/btrfs/send.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c index 77f9efc1f7aa..9a47b5598df7 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6196,8 +6196,13 @@ long btrfs_ioctl_send(struct file *mnt_file, void __user *arg_) 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; }