From 74412fd5d71b6eda0beb302aa467da000f0d530c Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Thu, 21 May 2015 15:11:12 +0800 Subject: [PATCH] crypto: scatterwalk - Check for same address in map_and_copy This patch adds a check for in scatterwalk_map_and_copy to avoid copying from the same address to the same address. This is going to be used for IV copying in AEAD IV generators. There is no provision for partial overlaps. This patch also uses the new scatterwalk_ffwd instead of doing it by hand in scatterwalk_map_and_copy. Signed-off-by: Herbert Xu --- crypto/scatterwalk.c | 16 ++++++---------- 1 file changed, 6 insertions(+), 10 deletions(-) diff --git a/crypto/scatterwalk.c b/crypto/scatterwalk.c index db920b59a6c3..8690324d3aef 100644 --- a/crypto/scatterwalk.c +++ b/crypto/scatterwalk.c @@ -104,22 +104,18 @@ void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, unsigned int start, unsigned int nbytes, int out) { struct scatter_walk walk; - unsigned int offset = 0; + struct scatterlist tmp[2]; if (!nbytes) return; - for (;;) { - scatterwalk_start(&walk, sg); - - if (start < offset + sg->length) - break; + sg = scatterwalk_ffwd(tmp, sg, start); - offset += sg->length; - sg = sg_next(sg); - } + if (sg_page(sg) == virt_to_page(buf) && + sg->offset == offset_in_page(buf)) + return; - scatterwalk_advance(&walk, start - offset); + scatterwalk_start(&walk, sg); scatterwalk_copychunks(buf, &walk, nbytes, out); scatterwalk_done(&walk, out, 0); } -- 2.20.1