[PATCH 4.18 239/350] crypto: aesni - dont use GFP_ATOMIC allocation if the request doesnt cross a page in gcm

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mikulas Patocka <mpatocka@xxxxxxxxxx>

commit a788848116454d753b13a4888e0e31ada3c4d393 upstream.

This patch fixes gcmaes_crypt_by_sg so that it won't use memory
allocation if the data doesn't cross a page boundary.

Authenticated encryption may be used by dm-crypt. If the encryption or
decryption fails, it would result in I/O error and filesystem corruption.
The function gcmaes_crypt_by_sg is using GFP_ATOMIC allocation that can
fail anytime. This patch fixes the logic so that it won't attempt the
failing allocation if the data doesn't cross a page boundary.

Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/crypto/aesni-intel_glue.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -817,7 +817,7 @@ static int gcmaes_crypt_by_sg(bool enc,
 	/* Linearize assoc, if not already linear */
 	if (req->src->length >= assoclen && req->src->length &&
 		(!PageHighMem(sg_page(req->src)) ||
-			req->src->offset + req->src->length < PAGE_SIZE)) {
+			req->src->offset + req->src->length <= PAGE_SIZE)) {
 		scatterwalk_start(&assoc_sg_walk, req->src);
 		assoc = scatterwalk_map(&assoc_sg_walk);
 	} else {