aboutsummaryrefslogtreecommitdiff
path: root/crypto
diff options
context:
space:
mode:
authorEric Biggers <ebiggers@google.com>2017-11-05 18:30:44 -0800
committerHerbert Xu <herbert@gondor.apana.org.au>2017-11-10 19:20:16 +0800
commit12d41a023efb01b846457ccdbbcbe2b65a87d530 (patch)
tree47083bc0d18c048f9fd9a336ed9479abffb401b9 /crypto
parentc3577f6100ca43261cd1d00cd46fde014c5b51ad (diff)
downloadlinux-stericsson-12d41a023efb01b846457ccdbbcbe2b65a87d530.tar.gz
crypto: dh - Fix double free of ctx->p
When setting the secret with the software Diffie-Hellman implementation, if allocating 'g' failed (e.g. if it was longer than MAX_EXTERN_MPI_BITS), then 'p' was freed twice: once immediately, and once later when the crypto_kpp tfm was destroyed. Fix it by using dh_free_ctx() (renamed to dh_clear_ctx()) in the error paths, as that correctly sets the pointers to NULL. KASAN report: MPI: mpi too large (32760 bits) ================================================================== BUG: KASAN: use-after-free in mpi_free+0x131/0x170 Read of size 4 at addr ffff88006c7cdf90 by task reproduce_doubl/367 CPU: 1 PID: 367 Comm: reproduce_doubl Not tainted 4.14.0-rc7-00040-g05298abde6fe #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: dump_stack+0xb3/0x10b ? mpi_free+0x131/0x170 print_address_description+0x79/0x2a0 ? mpi_free+0x131/0x170 kasan_report+0x236/0x340 ? akcipher_register_instance+0x90/0x90 __asan_report_load4_noabort+0x14/0x20 mpi_free+0x131/0x170 ? akcipher_register_instance+0x90/0x90 dh_exit_tfm+0x3d/0x140 crypto_kpp_exit_tfm+0x52/0x70 crypto_destroy_tfm+0xb3/0x250 __keyctl_dh_compute+0x640/0xe90 ? kasan_slab_free+0x12f/0x180 ? dh_data_from_key+0x240/0x240 ? key_create_or_update+0x1ee/0xb20 ? key_instantiate_and_link+0x440/0x440 ? lock_contended+0xee0/0xee0 ? kfree+0xcf/0x210 ? SyS_add_key+0x268/0x340 keyctl_dh_compute+0xb3/0xf1 ? __keyctl_dh_compute+0xe90/0xe90 ? SyS_add_key+0x26d/0x340 ? entry_SYSCALL_64_fastpath+0x5/0xbe ? trace_hardirqs_on_caller+0x3f4/0x560 SyS_keyctl+0x72/0x2c0 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x43ccf9 RSP: 002b:00007ffeeec96158 EFLAGS: 00000246 ORIG_RAX: 00000000000000fa RAX: ffffffffffffffda RBX: 000000000248b9b9 RCX: 000000000043ccf9 RDX: 00007ffeeec96170 RSI: 00007ffeeec96160 RDI: 0000000000000017 RBP: 0000000000000046 R08: 0000000000000000 R09: 0248b9b9143dc936 R10: 0000000000001000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000409670 R14: 0000000000409700 R15: 0000000000000000 Allocated by task 367: save_stack_trace+0x16/0x20 kasan_kmalloc+0xeb/0x180 kmem_cache_alloc_trace+0x114/0x300 mpi_alloc+0x4b/0x230 mpi_read_raw_data+0xbe/0x360 dh_set_secret+0x1dc/0x460 __keyctl_dh_compute+0x623/0xe90 keyctl_dh_compute+0xb3/0xf1 SyS_keyctl+0x72/0x2c0 entry_SYSCALL_64_fastpath+0x1f/0xbe Freed by task 367: save_stack_trace+0x16/0x20 kasan_slab_free+0xab/0x180 kfree+0xb5/0x210 mpi_free+0xcb/0x170 dh_set_secret+0x2d7/0x460 __keyctl_dh_compute+0x623/0xe90 keyctl_dh_compute+0xb3/0xf1 SyS_keyctl+0x72/0x2c0 entry_SYSCALL_64_fastpath+0x1f/0xbe Fixes: 802c7f1c84e4 ("crypto: dh - Add DH software implementation") Cc: <stable@vger.kernel.org> # v4.8+ Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/dh.c33
1 files changed, 13 insertions, 20 deletions
diff --git a/crypto/dh.c b/crypto/dh.c
index b1032a5c1bfa..aadaf36fb56f 100644
--- a/crypto/dh.c
+++ b/crypto/dh.c
@@ -21,19 +21,12 @@ struct dh_ctx {
MPI xa;
};
-static inline void dh_clear_params(struct dh_ctx *ctx)
+static void dh_clear_ctx(struct dh_ctx *ctx)
{
mpi_free(ctx->p);
mpi_free(ctx->g);
- ctx->p = NULL;
- ctx->g = NULL;
-}
-
-static void dh_free_ctx(struct dh_ctx *ctx)
-{
- dh_clear_params(ctx);
mpi_free(ctx->xa);
- ctx->xa = NULL;
+ memset(ctx, 0, sizeof(*ctx));
}
/*
@@ -71,10 +64,8 @@ static int dh_set_params(struct dh_ctx *ctx, struct dh *params)
return -EINVAL;
ctx->g = mpi_read_raw_data(params->g, params->g_size);
- if (!ctx->g) {
- mpi_free(ctx->p);
+ if (!ctx->g)
return -EINVAL;
- }
return 0;
}
@@ -86,21 +77,23 @@ static int dh_set_secret(struct crypto_kpp *tfm, const void *buf,
struct dh params;
/* Free the old MPI key if any */
- dh_free_ctx(ctx);
+ dh_clear_ctx(ctx);
if (crypto_dh_decode_key(buf, len, &params) < 0)
- return -EINVAL;
+ goto err_clear_ctx;
if (dh_set_params(ctx, &params) < 0)
- return -EINVAL;
+ goto err_clear_ctx;
ctx->xa = mpi_read_raw_data(params.key, params.key_size);
- if (!ctx->xa) {
- dh_clear_params(ctx);
- return -EINVAL;
- }
+ if (!ctx->xa)
+ goto err_clear_ctx;
return 0;
+
+err_clear_ctx:
+ dh_clear_ctx(ctx);
+ return -EINVAL;
}
static int dh_compute_value(struct kpp_request *req)
@@ -158,7 +151,7 @@ static void dh_exit_tfm(struct crypto_kpp *tfm)
{
struct dh_ctx *ctx = dh_get_ctx(tfm);
- dh_free_ctx(ctx);
+ dh_clear_ctx(ctx);
}
static struct kpp_alg dh = {