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authorFilipe Manana <fdmanana@suse.com>2018-10-13 00:37:25 +0100
committerDavid Sterba <dsterba@suse.com>2018-10-17 17:42:46 +0200
commit3527a018c00e5dbada2f9d7ed5576437b6dd5cfb (patch)
tree03ba27ac5ed2e2aa7d70c10b8bf9f2a9cfe18867 /fs/btrfs
parentd9352794dad9f28535439d85a815978878c141ab (diff)
downloadlinux-3527a018c00e5dbada2f9d7ed5576437b6dd5cfb.tar.bz2
Btrfs: fix null pointer dereference on compressed write path error
At inode.c:compress_file_range(), under the "free_pages_out" label, we can end up dereferencing the "pages" pointer when it has a NULL value. This case happens when "start" has a value of 0 and we fail to allocate memory for the "pages" pointer. When that happens we jump to the "cont" label and then enter the "if (start == 0)" branch where we immediately call the cow_file_range_inline() function. If that function returns 0 (success creating an inline extent) or an error (like -ENOMEM for example) we jump to the "free_pages_out" label and then access "pages[i]" leading to a NULL pointer dereference, since "nr_pages" has a value greater than zero at that point. Fix this by setting "nr_pages" to 0 when we fail to allocate memory for the "pages" pointer. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=201119 Fixes: 771ed689d2cd ("Btrfs: Optimize compressed writeback and reads") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Liu Bo <bo.liu@linux.alibaba.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/inode.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f22f77172c5f..f98ddd886036 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -502,6 +502,7 @@ again:
pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
if (!pages) {
/* just bail out to the uncompressed code */
+ nr_pages = 0;
goto cont;
}