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authorDan Carpenter <dan.carpenter@oracle.com>2017-03-17 23:51:20 +0300
committerDavid Sterba <dsterba@suse.com>2017-03-29 15:29:08 +0300
commit457ae7268b29c33dee1c0feb143a15f6029d177b (patch)
treea1ebc64a816a1da2a67e01d928582b41eb48a611 /fs/btrfs/send.c
parentce0dcee626c482183b42d45b6ea43198c7223fc7 (diff)
downloadlinux-457ae7268b29c33dee1c0feb143a15f6029d177b.tar.xz
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 <dan.carpenter@oracle.com> Reviewed-by: David Sterba <dsterba@suse.com> [ added comment ] Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/send.c')
-rw-r--r--fs/btrfs/send.c7
1 files changed, 6 insertions, 1 deletions
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;
}