From 457ae7268b29c33dee1c0feb143a15f6029d177b Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 17 Mar 2017 23:51:20 +0300 Subject: [PATCH] Btrfs: fix an integer overflow check 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 Reviewed-by: David Sterba [ added comment ] Signed-off-by: David Sterba --- 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 456c8901489b..a60d5bfb8a49 100644 --- a/fs/btrfs/send.c +++ b/fs/btrfs/send.c @@ -6305,8 +6305,13 @@ 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; } -- 2.20.1