From: Hongbo Li herberthbli@tencent.com
stable inclusion from linux-4.19.207 commit ab642cd7bf1859569dc93a67db980bf883096ab5
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[ Upstream commit b6f756726e4dfe75be1883f6a0202dcecdc801ab ]
We should set the additional space to 0 in mpi_resize(). So use kcalloc() instead of kmalloc_array().
In lib/mpi/ec.c: /**************** * Resize the array of A to NLIMBS. the additional space is cleared * (set to 0) [done by m_realloc()] */ int mpi_resize(MPI a, unsigned nlimbs)
Like the comment of kernel's mpi_resize() said, the additional space need to be set to 0, but when a->d is not NULL, it does not set.
The kernel's mpi lib is from libgcrypt, the mpi resize in libgcrypt is _gcry_mpi_resize() which set the additional space to 0.
This bug may cause mpi api which use mpi_resize() get wrong result under the condition of using the additional space without initiation. If this condition is not met, the bug would not be triggered. Currently in kernel, rsa, sm2 and dh use mpi lib, and they works well, so the bug is not triggered in these cases.
add_points_edwards() use the additional space directly, so it will get a wrong result.
Fixes: cdec9cb5167a ("crypto: GnuPG based MPI lib - source files (part 1)") Signed-off-by: Hongbo Li herberthbli@tencent.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- lib/mpi/mpiutil.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/mpi/mpiutil.c b/lib/mpi/mpiutil.c index 20ed0f7667871..00825028cc847 100644 --- a/lib/mpi/mpiutil.c +++ b/lib/mpi/mpiutil.c @@ -91,7 +91,7 @@ int mpi_resize(MPI a, unsigned nlimbs) return 0; /* no need to do it */
if (a->d) { - p = kmalloc_array(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); + p = kcalloc(nlimbs, sizeof(mpi_limb_t), GFP_KERNEL); if (!p) return -ENOMEM; memcpy(p, a->d, a->alloced * sizeof(mpi_limb_t));