The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e49be14b8d80e23bb7c53d78c21717a474ade76b Mon Sep 17 00:00:00 2001

From: Dan Robertson dan@dlrobertson.com Date: Tue, 19 Feb 2019 02:56:43 +0000 Subject: [PATCH] btrfs: init csum_list before possible free

The scrub_ctx csum_list member must be initialized before scrub_free_ctx is called. If the csum_list is not initialized beforehand, the list_empty call in scrub_free_csums will result in a null deref if the allocation fails in the for loop.

Fixes: a2de733c78fa ("btrfs: scrub") CC: stable@vger.kernel.org # 3.0+ Reviewed-by: Nikolay Borisov nborisov@suse.com Signed-off-by: Dan Robertson dan@dlrobertson.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index 669bedfec4a9..a99588536c79 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -584,6 +584,7 @@ static noinline_for_stack struct scrub_ctx *scrub_setup_ctx( sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO; sctx->curr = -1; sctx->fs_info = fs_info; + INIT_LIST_HEAD(&sctx->csum_list); for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) { struct scrub_bio *sbio;

@@ -608,7 +609,6 @@ static noinline_for_stack struct scrub_ctx *scrub_setup_ctx( atomic_set(&sctx->workers_pending, 0); atomic_set(&sctx->cancel_req, 0); sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy); - INIT_LIST_HEAD(&sctx->csum_list);

spin_lock_init(&sctx->list_lock); spin_lock_init(&sctx->stat_lock);