From 2b95fda2c4fcb6d6625963f889247538f247fce0 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 24 Nov 2016 13:23:03 +0000 Subject: X.509: Fix double free in x509_cert_parse() [ver #3] We shouldn't free cert->pub->key in x509_cert_parse() because x509_free_certificate() also does this: BUG: Double free or freeing an invalid pointer ... Call Trace: [] dump_stack+0x63/0x83 [] kasan_object_err+0x21/0x70 [] kasan_report_double_free+0x49/0x60 [] kasan_slab_free+0x9d/0xc0 [] kfree+0x8a/0x1a0 [] public_key_free+0x1f/0x30 [] x509_free_certificate+0x24/0x90 [] x509_cert_parse+0x2bc/0x300 [] x509_key_preparse+0x3e/0x330 [] asymmetric_key_preparse+0x6f/0x100 [] key_create_or_update+0x260/0x5f0 [] SyS_add_key+0x199/0x2a0 [] entry_SYSCALL_64_fastpath+0x1e/0xad Object at ffff880110bd1900, in cache kmalloc-512 size: 512 .... Freed: PID = 2579 [] save_stack_trace+0x1b/0x20 [] save_stack+0x46/0xd0 [] kasan_slab_free+0x73/0xc0 [] kfree+0x8a/0x1a0 [] x509_cert_parse+0x2a3/0x300 [] x509_key_preparse+0x3e/0x330 [] asymmetric_key_preparse+0x6f/0x100 [] key_create_or_update+0x260/0x5f0 [] SyS_add_key+0x199/0x2a0 [] entry_SYSCALL_64_fastpath+0x1e/0xad Fixes: db6c43bd2132 ("crypto: KEYS: convert public key and digsig asym to the akcipher api") Signed-off-by: Andrey Ryabinin Cc: Signed-off-by: David Howells Signed-off-by: James Morris --- crypto/asymmetric_keys/x509_cert_parser.c | 1 - 1 file changed, 1 deletion(-) diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c index 865f46ea724f..c80765b211cf 100644 --- a/crypto/asymmetric_keys/x509_cert_parser.c +++ b/crypto/asymmetric_keys/x509_cert_parser.c @@ -133,7 +133,6 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen) return cert; error_decode: - kfree(cert->pub->key); kfree(ctx); error_no_ctx: x509_free_certificate(cert); -- cgit v1.2.3 From f5527fffff3f002b0a6b376163613b82f69de073 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 24 Nov 2016 13:23:10 +0000 Subject: mpi: Fix NULL ptr dereference in mpi_powm() [ver #3] This fixes CVE-2016-8650. If mpi_powm() is given a zero exponent, it wants to immediately return either 1 or 0, depending on the modulus. However, if the result was initalised with zero limb space, no limbs space is allocated and a NULL-pointer exception ensues. Fix this by allocating a minimal amount of limb space for the result when the 0-exponent case when the result is 1 and not touching the limb space when the result is 0. This affects the use of RSA keys and X.509 certificates that carry them. BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] mpi_powm+0x32/0x7e6 PGD 0 Oops: 0002 [#1] SMP Modules linked in: CPU: 3 PID: 3014 Comm: keyctl Not tainted 4.9.0-rc6-fscache+ #278 Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 task: ffff8804011944c0 task.stack: ffff880401294000 RIP: 0010:[] [] mpi_powm+0x32/0x7e6 RSP: 0018:ffff880401297ad8 EFLAGS: 00010212 RAX: 0000000000000000 RBX: ffff88040868bec0 RCX: ffff88040868bba0 RDX: ffff88040868b260 RSI: ffff88040868bec0 RDI: ffff88040868bee0 RBP: ffff880401297ba8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000047 R11: ffffffff8183b210 R12: 0000000000000000 R13: ffff8804087c7600 R14: 000000000000001f R15: ffff880401297c50 FS: 00007f7a7918c700(0000) GS:ffff88041fb80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000401250000 CR4: 00000000001406e0 Stack: ffff88040868bec0 0000000000000020 ffff880401297b00 ffffffff81376cd4 0000000000000100 ffff880401297b10 ffffffff81376d12 ffff880401297b30 ffffffff81376f37 0000000000000100 0000000000000000 ffff880401297ba8 Call Trace: [] ? __sg_page_iter_next+0x43/0x66 [] ? sg_miter_get_next_page+0x1b/0x5d [] ? sg_miter_next+0x17/0xbd [] ? mpi_read_raw_from_sgl+0xf2/0x146 [] rsa_verify+0x9d/0xee [] ? pkcs1pad_sg_set_buf+0x2e/0xbb [] pkcs1pad_verify+0xc0/0xe1 [] public_key_verify_signature+0x1b0/0x228 [] x509_check_for_self_signed+0xa1/0xc4 [] x509_cert_parse+0x167/0x1a1 [] x509_key_preparse+0x21/0x1a1 [] asymmetric_key_preparse+0x34/0x61 [] key_create_or_update+0x145/0x399 [] SyS_add_key+0x154/0x19e [] do_syscall_64+0x80/0x191 [] entry_SYSCALL64_slow_path+0x25/0x25 Code: 56 41 55 41 54 53 48 81 ec a8 00 00 00 44 8b 71 04 8b 42 04 4c 8b 67 18 45 85 f6 89 45 80 0f 84 b4 06 00 00 85 c0 75 2f 41 ff ce <49> c7 04 24 01 00 00 00 b0 01 75 0b 48 8b 41 18 48 83 38 01 0f RIP [] mpi_powm+0x32/0x7e6 RSP CR2: 0000000000000000 ---[ end trace d82015255d4a5d8d ]--- Basically, this is a backport of a libgcrypt patch: http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libgcrypt.git;a=patch;h=6e1adb05d290aeeb1c230c763970695f4a538526 Fixes: cdec9cb5167a ("crypto: GnuPG based MPI lib - source files (part 1)") Signed-off-by: Andrey Ryabinin Signed-off-by: David Howells cc: Dmitry Kasatkin cc: linux-ima-devel@lists.sourceforge.net cc: stable@vger.kernel.org Signed-off-by: James Morris --- lib/mpi/mpi-pow.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/lib/mpi/mpi-pow.c b/lib/mpi/mpi-pow.c index 5464c8744ea9..e24388a863a7 100644 --- a/lib/mpi/mpi-pow.c +++ b/lib/mpi/mpi-pow.c @@ -64,8 +64,13 @@ int mpi_powm(MPI res, MPI base, MPI exp, MPI mod) if (!esize) { /* Exponent is zero, result is 1 mod MOD, i.e., 1 or 0 * depending on if MOD equals 1. */ - rp[0] = 1; res->nlimbs = (msize == 1 && mod->d[0] == 1) ? 0 : 1; + if (res->nlimbs) { + if (mpi_resize(res, 1) < 0) + goto enomem; + rp = res->d; + rp[0] = 1; + } res->sign = 0; goto leave; } -- cgit v1.2.3