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crypto: algif_skcipher - only call put_page on referenced and used pages 

For asynchronous operation, SGs are allocated without a page mapped to
them or with a page that is not used (ref-counted). If the SGL is freed,
the code must only call put_page for an SG if there was a page assigned
and ref-counted in the first place.

This fixes a kernel crash when using io_submit with more than one iocb
using the sendmsg and sendpage (vmsplice/splice) interface.

Cc: <stable@vger.kernel.org>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Stephan Mueller 2017-08-16 11:56:24 +02:00 committed by Herbert Xu
parent 549f64153c
commit 445a582738
1 changed files with 7 additions and 2 deletions
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9
crypto/algif_skcipher.c
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@ -87,8 +87,13 @@ static void skcipher_free_async_sgls(struct skcipher_async_req *sreq)
}
sgl = sreq->tsg;
n = sg_nents(sgl);
for_each_sg(sgl, sg, n, i)
put_page(sg_page(sg));
for_each_sg(sgl, sg, n, i) {
struct page *page = sg_page(sg);
/* some SGs may not have a page mapped */
if (page && page_ref_count(page))
put_page(page);
}
kfree(sreq->tsg);
}