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0868def3e4
Like the skcipher_walk case:
scatterwalk_done() is only meant to be called after a nonzero number of
bytes have been processed, since scatterwalk_pagedone() will flush the
dcache of the *previous* page. But in the error case of
blkcipher_walk_done(), e.g. if the input wasn't an integer number of
blocks, scatterwalk_done() was actually called after advancing 0 bytes.
This caused a crash ("BUG: unable to handle kernel paging request")
during '!PageSlab(page)' on architectures like arm and arm64 that define
ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE, provided that the input was
page-aligned as in that case walk->offset == 0.
Fix it by reorganizing blkcipher_walk_done() to skip the
scatterwalk_advance() and scatterwalk_done() if an error has occurred.
This bug was found by syzkaller fuzzing.
Reproducer, assuming ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE:
#include <linux/if_alg.h>
#include <sys/socket.h>
#include <unistd.h>
int main()
{
struct sockaddr_alg addr = {
.salg_type = "skcipher",
.salg_name = "ecb(aes-generic)",
};
char buffer[4096] __attribute__((aligned(4096))) = { 0 };
int fd;
fd = socket(AF_ALG, SOCK_SEQPACKET, 0);
bind(fd, (void *)&addr, sizeof(addr));
setsockopt(fd, SOL_ALG, ALG_SET_KEY, buffer, 16);
fd = accept(fd, NULL, NULL);
write(fd, buffer, 15);
read(fd, buffer, 15);
}
Reported-by: Liu Chao <liuchao741@huawei.com>
Fixes: 5cde0af2a982 ("[CRYPTO] cipher: Added block cipher type")
Cc: <stable@vger.kernel.org> # v2.6.19+
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.