lib/mpi: kunmap after finishing accessing buffer

Using sg_miter_start and sg_miter_next, the buffer of an SG is kmap'ed
to *buff. The current code calls sg_miter_stop (and thus kunmap) on the
SG entry before the last access of *buff.

The patch moves the sg_miter_stop call after the last access to *buff to
ensure that the memory pointed to by *buff is still mapped.

Fixes: 4816c9406430 ("lib/mpi: Fix SG miter leak")
Cc: <stable@vger.kernel.org>
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index 5a0f75a3bf01c1b259fb125fbe7266c186d83a71..eead4b339466854f51db30a17f17ee0472ebe6d3 100644 (file)
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -364,11 +364,11 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
        }
 
        miter.consumed = lzeros;
-       sg_miter_stop(&miter);
 
        nbytes -= lzeros;
        nbits = nbytes * 8;
        if (nbits > MAX_EXTERN_MPI_BITS) {
+               sg_miter_stop(&miter);
                pr_info("MPI: mpi too large (%u bits)\n", nbits);
                return NULL;
        }
@@ -376,6 +376,8 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
        if (nbytes > 0)
                nbits -= count_leading_zeros(*buff) - (BITS_PER_LONG - 8);
 
+       sg_miter_stop(&miter);
+
        nlimbs = DIV_ROUND_UP(nbytes, BYTES_PER_MPI_LIMB);
        val = mpi_alloc(nlimbs);
        if (!val)