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Eric Biggers d2890c3778 crypto: rsa - fix buffer overread when stripping leading zeroes
In rsa_get_n(), if the buffer contained all 0's and "FIPS mode" is
enabled, we would read one byte past the end of the buffer while
scanning the leading zeroes.  Fix it by checking 'n_sz' before '!*ptr'.

This bug was reachable by adding a specially crafted key of type
"asymmetric" (requires CONFIG_RSA and CONFIG_X509_CERTIFICATE_PARSER).

KASAN report:

    BUG: KASAN: slab-out-of-bounds in rsa_get_n+0x19e/0x1d0 crypto/rsa_helper.c:33
    Read of size 1 at addr ffff88003501a708 by task keyctl/196

    CPU: 1 PID: 196 Comm: keyctl Not tainted 4.14.0-09238-g1d3b78bbc6e9 #26
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-20171110_100015-anatol 04/01/2014
    Call Trace:
     rsa_get_n+0x19e/0x1d0 crypto/rsa_helper.c:33
     asn1_ber_decoder+0x82a/0x1fd0 lib/asn1_decoder.c:328
     rsa_set_pub_key+0xd3/0x320 crypto/rsa.c:278
     crypto_akcipher_set_pub_key ./include/crypto/akcipher.h:364 [inline]
     pkcs1pad_set_pub_key+0xae/0x200 crypto/rsa-pkcs1pad.c:117
     crypto_akcipher_set_pub_key ./include/crypto/akcipher.h:364 [inline]
     public_key_verify_signature+0x270/0x9d0 crypto/asymmetric_keys/public_key.c:106
     x509_check_for_self_signed+0x2ea/0x480 crypto/asymmetric_keys/x509_public_key.c:141
     x509_cert_parse+0x46a/0x620 crypto/asymmetric_keys/x509_cert_parser.c:129
     x509_key_preparse+0x61/0x750 crypto/asymmetric_keys/x509_public_key.c:174
     asymmetric_key_preparse+0xa4/0x150 crypto/asymmetric_keys/asymmetric_type.c:388
     key_create_or_update+0x4d4/0x10a0 security/keys/key.c:850
     SYSC_add_key security/keys/keyctl.c:122 [inline]
     SyS_add_key+0xe8/0x290 security/keys/keyctl.c:62
     entry_SYSCALL_64_fastpath+0x1f/0x96

    Allocated by task 196:
     __do_kmalloc mm/slab.c:3711 [inline]
     __kmalloc_track_caller+0x118/0x2e0 mm/slab.c:3726
     kmemdup+0x17/0x40 mm/util.c:118
     kmemdup ./include/linux/string.h:414 [inline]
     x509_cert_parse+0x2cb/0x620 crypto/asymmetric_keys/x509_cert_parser.c:106
     x509_key_preparse+0x61/0x750 crypto/asymmetric_keys/x509_public_key.c:174
     asymmetric_key_preparse+0xa4/0x150 crypto/asymmetric_keys/asymmetric_type.c:388
     key_create_or_update+0x4d4/0x10a0 security/keys/key.c:850
     SYSC_add_key security/keys/keyctl.c:122 [inline]
     SyS_add_key+0xe8/0x290 security/keys/keyctl.c:62
     entry_SYSCALL_64_fastpath+0x1f/0x96

Fixes: 5a7de97309 ("crypto: rsa - return raw integers for the ASN.1 parser")
Cc: <stable@vger.kernel.org> # v4.8+
Cc: Tudor Ambarus <tudor-dan.ambarus@nxp.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-11-29 13:39:14 +11:00
arch Merge branch 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-26 15:03:49 -08:00
block treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto crypto: rsa - fix buffer overread when stripping leading zeroes 2017-11-29 13:39:14 +11:00
Documentation Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:11:54 -08:00
drivers Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:39:20 -08:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-25 08:37:16 -10:00
include Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:39:20 -08:00
init EXPERT Kconfig menu: fix broken EXPERT menu 2017-11-17 16:10:05 -08:00
ipc Merge branch 'akpm' (patches from Andrew) 2017-11-17 16:56:17 -08:00
kernel Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:39:20 -08:00
lib Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-25 08:37:16 -10:00
mm block/laptop_mode: Convert timers to use timer_setup() 2017-11-21 15:46:44 -08:00
net Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-25 08:37:16 -10:00
samples kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
scripts Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-25 08:37:16 -10:00
security Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-25 08:37:16 -10:00
sound Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-25 08:37:16 -10:00
tools Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-11-26 14:11:54 -08:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt Trimmed second batch of KVM changes for Linux 4.15 2017-11-24 19:44:25 -10:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild misc updates for v4.15 2017-11-17 17:51:33 -08:00
.mailmap Add Jason Gunthorpe as co-maintainer of the RDMA stack 2017-11-17 09:36:18 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS RTC for 4.15 2017-11-22 20:58:23 -10:00
Makefile Linux 4.15-rc1 2017-11-26 16:01:47 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
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See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
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