| From: Herbert Xu <herbert@gondor.apana.org.au> |
| Date: Mon, 24 Jun 2019 18:32:26 +0800 |
| Subject: lib/mpi: Fix karactx leak in mpi_powm |
| |
| commit c8ea9fce2baf7b643384f36f29e4194fa40d33a6 upstream. |
| |
| Sometimes mpi_powm will leak karactx because a memory allocation |
| failure causes a bail-out that skips the freeing of karactx. This |
| patch moves the freeing of karactx to the end of the function like |
| everything else so that it can't be skipped. |
| |
| Reported-by: syzbot+f7baccc38dcc1e094e77@syzkaller.appspotmail.com |
| Fixes: cdec9cb5167a ("crypto: GnuPG based MPI lib - source files...") |
| Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> |
| Reviewed-by: Eric Biggers <ebiggers@kernel.org> |
| Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| lib/mpi/mpi-pow.c | 6 ++---- |
| 1 file changed, 2 insertions(+), 4 deletions(-) |
| |
| --- a/lib/mpi/mpi-pow.c |
| +++ b/lib/mpi/mpi-pow.c |
| @@ -36,6 +36,7 @@ |
| int mpi_powm(MPI res, MPI base, MPI exp, MPI mod) |
| { |
| mpi_ptr_t mp_marker = NULL, bp_marker = NULL, ep_marker = NULL; |
| + struct karatsuba_ctx karactx = {}; |
| mpi_ptr_t xp_marker = NULL; |
| mpi_ptr_t tspace = NULL; |
| mpi_ptr_t rp, ep, mp, bp; |
| @@ -163,13 +164,11 @@ int mpi_powm(MPI res, MPI base, MPI exp, |
| int c; |
| mpi_limb_t e; |
| mpi_limb_t carry_limb; |
| - struct karatsuba_ctx karactx; |
| |
| xp = xp_marker = mpi_alloc_limb_space(2 * (msize + 1)); |
| if (!xp) |
| goto enomem; |
| |
| - memset(&karactx, 0, sizeof karactx); |
| negative_result = (ep[0] & 1) && base->sign; |
| |
| i = esize - 1; |
| @@ -293,8 +292,6 @@ int mpi_powm(MPI res, MPI base, MPI exp, |
| if (mod_shift_cnt) |
| mpihelp_rshift(rp, rp, rsize, mod_shift_cnt); |
| MPN_NORMALIZE(rp, rsize); |
| - |
| - mpihelp_release_karatsuba_ctx(&karactx); |
| } |
| |
| if (negative_result && rsize) { |
| @@ -311,6 +308,7 @@ int mpi_powm(MPI res, MPI base, MPI exp, |
| leave: |
| rc = 0; |
| enomem: |
| + mpihelp_release_karatsuba_ctx(&karactx); |
| if (assign_rp) |
| mpi_assign_limb_space(res, rp, size); |
| if (mp_marker) |