From 24f1713777f02300d0c48ddc142b2c711e462b65 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Wed, 27 Jul 2016 22:30:52 +0200 Subject: [PATCH] btrfs-progs: fix unaligned access calculating raid56 data The extent_buffer::data might be unaligned wrt unsigned long, depends on acutal layout of the structure and width of the int types. Use explicit unaligned access helpers. Reported-by: Anatoly Pugachev Signed-off-by: David Sterba --- volumes.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/volumes.c b/volumes.c index b42a412..26bf6c5 100644 --- a/volumes.c +++ b/volumes.c @@ -2154,9 +2154,14 @@ int write_raid56_with_parity(struct btrfs_fs_info *info, ebs[multi->num_stripes - 1] = p_eb; memcpy(p_eb->data, ebs[0]->data, stripe_len); for (j = 1; j < multi->num_stripes - 1; j++) { - for (i = 0; i < stripe_len; i += sizeof(unsigned long)) { - *(unsigned long *)(p_eb->data + i) ^= - *(unsigned long *)(ebs[j]->data + i); + for (i = 0; i < stripe_len; i += sizeof(u64)) { + u64 p_eb_data; + u64 ebs_data; + + p_eb_data = get_unaligned_64(p_eb->data + i); + ebs_data = get_unaligned_64(ebs[j]->data + i); + p_eb_data ^= ebs_data; + put_unaligned_64(p_eb_data, p_eb->data + i); } } } -- 2.7.4