* [PATCH 0/2] KEYS: Fixes [ver #3]
@ 2016-11-24 13:22 David Howells
2016-11-24 13:23 ` [PATCH 1/2] X.509: Fix double free in x509_cert_parse() " David Howells
2016-11-24 13:23 ` [PATCH 2/2] mpi: Fix NULL ptr dereference in mpi_powm() " David Howells
0 siblings, 2 replies; 3+ messages in thread
From: David Howells @ 2016-11-24 13:22 UTC (permalink / raw)
To: jmorris
Cc: dhowells, linux-security-module, keyrings, linux-kernel, linux-crypto
Hi James,
Can you pull these patches please and pass them on to Linus? They include
the following:
(1) Fix mpi_powm()'s handling of a number with a zero exponent [CVE-2016-8650].
(2) Fix double free in X.509 error handling.
Ver #3:
- Integrate my and Andrey's patches for mpi_powm() and use mpi_resize()
instead of RESIZE_IF_NEEDED() - the latter adds a duplicate check into
the execution path of a trivial case we don't normally expect to be
taken.
Ver #2:
- Use RESIZE_IF_NEEDED() to conditionally resize the result rather than
manually doing this.
The patches can be found here also:
http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=keys-fixes
Tagged thusly:
git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
keys-fixes-20161124-3
David
---
Andrey Ryabinin (2):
X.509: Fix double free in x509_cert_parse()
mpi: Fix NULL ptr dereference in mpi_powm()
crypto/asymmetric_keys/x509_cert_parser.c | 1 -
lib/mpi/mpi-pow.c | 7 ++++++-
2 files changed, 6 insertions(+), 2 deletions(-)
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH 1/2] X.509: Fix double free in x509_cert_parse() [ver #3]
2016-11-24 13:22 [PATCH 0/2] KEYS: Fixes [ver #3] David Howells
@ 2016-11-24 13:23 ` David Howells
2016-11-24 13:23 ` [PATCH 2/2] mpi: Fix NULL ptr dereference in mpi_powm() " David Howells
1 sibling, 0 replies; 3+ messages in thread
From: David Howells @ 2016-11-24 13:23 UTC (permalink / raw)
To: jmorris
Cc: linux-kernel, stable, dhowells, linux-security-module, keyrings,
linux-crypto, Andrey Ryabinin
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
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:
[<ffffffff81896c20>] dump_stack+0x63/0x83
[<ffffffff81356571>] kasan_object_err+0x21/0x70
[<ffffffff81356ed9>] kasan_report_double_free+0x49/0x60
[<ffffffff813561ad>] kasan_slab_free+0x9d/0xc0
[<ffffffff81350b7a>] kfree+0x8a/0x1a0
[<ffffffff81844fbf>] public_key_free+0x1f/0x30
[<ffffffff818455d4>] x509_free_certificate+0x24/0x90
[<ffffffff818460bc>] x509_cert_parse+0x2bc/0x300
[<ffffffff81846cae>] x509_key_preparse+0x3e/0x330
[<ffffffff818444cf>] asymmetric_key_preparse+0x6f/0x100
[<ffffffff8178bec0>] key_create_or_update+0x260/0x5f0
[<ffffffff8178e6d9>] SyS_add_key+0x199/0x2a0
[<ffffffff821d823b>] entry_SYSCALL_64_fastpath+0x1e/0xad
Object at ffff880110bd1900, in cache kmalloc-512 size: 512
....
Freed:
PID = 2579
[<ffffffff8104283b>] save_stack_trace+0x1b/0x20
[<ffffffff813558f6>] save_stack+0x46/0xd0
[<ffffffff81356183>] kasan_slab_free+0x73/0xc0
[<ffffffff81350b7a>] kfree+0x8a/0x1a0
[<ffffffff818460a3>] x509_cert_parse+0x2a3/0x300
[<ffffffff81846cae>] x509_key_preparse+0x3e/0x330
[<ffffffff818444cf>] asymmetric_key_preparse+0x6f/0x100
[<ffffffff8178bec0>] key_create_or_update+0x260/0x5f0
[<ffffffff8178e6d9>] SyS_add_key+0x199/0x2a0
[<ffffffff821d823b>] 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 <aryabinin@virtuozzo.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Howells <dhowells@redhat.com>
---
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);
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 2/2] mpi: Fix NULL ptr dereference in mpi_powm() [ver #3]
2016-11-24 13:22 [PATCH 0/2] KEYS: Fixes [ver #3] David Howells
2016-11-24 13:23 ` [PATCH 1/2] X.509: Fix double free in x509_cert_parse() " David Howells
@ 2016-11-24 13:23 ` David Howells
1 sibling, 0 replies; 3+ messages in thread
From: David Howells @ 2016-11-24 13:23 UTC (permalink / raw)
To: jmorris
Cc: Dmitry Kasatkin, linux-kernel, stable, dhowells,
linux-security-module, keyrings, linux-crypto, linux-ima-devel,
Andrey Ryabinin
From: Andrey Ryabinin <aryabinin@virtuozzo.com>
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: [<ffffffff8138ce5d>] 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:[<ffffffff8138ce5d>] [<ffffffff8138ce5d>] 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:
[<ffffffff81376cd4>] ? __sg_page_iter_next+0x43/0x66
[<ffffffff81376d12>] ? sg_miter_get_next_page+0x1b/0x5d
[<ffffffff81376f37>] ? sg_miter_next+0x17/0xbd
[<ffffffff8138ba3a>] ? mpi_read_raw_from_sgl+0xf2/0x146
[<ffffffff8132a95c>] rsa_verify+0x9d/0xee
[<ffffffff8132acca>] ? pkcs1pad_sg_set_buf+0x2e/0xbb
[<ffffffff8132af40>] pkcs1pad_verify+0xc0/0xe1
[<ffffffff8133cb5e>] public_key_verify_signature+0x1b0/0x228
[<ffffffff8133d974>] x509_check_for_self_signed+0xa1/0xc4
[<ffffffff8133cdde>] x509_cert_parse+0x167/0x1a1
[<ffffffff8133d609>] x509_key_preparse+0x21/0x1a1
[<ffffffff8133c3d7>] asymmetric_key_preparse+0x34/0x61
[<ffffffff812fc9f3>] key_create_or_update+0x145/0x399
[<ffffffff812fe227>] SyS_add_key+0x154/0x19e
[<ffffffff81001c2b>] do_syscall_64+0x80/0x191
[<ffffffff816825e4>] 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 [<ffffffff8138ce5d>] mpi_powm+0x32/0x7e6
RSP <ffff880401297ad8>
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 <aryabinin@virtuozzo.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
cc: linux-ima-devel@lists.sourceforge.net
cc: stable@vger.kernel.org
---
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;
}
^ permalink raw reply related [flat|nested] 3+ messages in thread
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Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2016-11-24 13:22 [PATCH 0/2] KEYS: Fixes [ver #3] David Howells
2016-11-24 13:23 ` [PATCH 1/2] X.509: Fix double free in x509_cert_parse() " David Howells
2016-11-24 13:23 ` [PATCH 2/2] mpi: Fix NULL ptr dereference in mpi_powm() " David Howells
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