Revision 624f5ab8720b3371367327a822c267699c1823b8 authored by Eric Biggers on 07 November 2017, 22:29:02 UTC, committed by James Morris on 08 November 2017, 13:38:21 UTC
syzkaller reported a NULL pointer dereference in asn1_ber_decoder(). It can be reproduced by the following command, assuming CONFIG_PKCS7_TEST_KEY=y: keyctl add pkcs7_test desc '' @s The bug is that if the data buffer is empty, an integer underflow occurs in the following check: if (unlikely(dp >= datalen - 1)) goto data_overrun_error; This results in the NULL data pointer being dereferenced. Fix it by checking for 'datalen - dp < 2' instead. Also fix the similar check for 'dp >= datalen - n' later in the same function. That one possibly could result in a buffer overread. The NULL pointer dereference was reproducible using the "pkcs7_test" key type but not the "asymmetric" key type because the "asymmetric" key type checks for a 0-length payload before calling into the ASN.1 decoder but the "pkcs7_test" key type does not. The bug report was: BUG: unable to handle kernel NULL pointer dereference at (null) IP: asn1_ber_decoder+0x17f/0xe60 lib/asn1_decoder.c:233 PGD 7b708067 P4D 7b708067 PUD 7b6ee067 PMD 0 Oops: 0000 [#1] SMP Modules linked in: CPU: 0 PID: 522 Comm: syz-executor1 Not tainted 4.14.0-rc8 #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.3-20171021_125229-anatol 04/01/2014 task: ffff9b6b3798c040 task.stack: ffff9b6b37970000 RIP: 0010:asn1_ber_decoder+0x17f/0xe60 lib/asn1_decoder.c:233 RSP: 0018:ffff9b6b37973c78 EFLAGS: 00010216 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000021c RDX: ffffffff814a04ed RSI: ffffb1524066e000 RDI: ffffffff910759e0 RBP: ffff9b6b37973d60 R08: 0000000000000001 R09: ffff9b6b3caa4180 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 FS: 00007f10ed1f2700(0000) GS:ffff9b6b3ea00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000007b6f3000 CR4: 00000000000006f0 Call Trace: pkcs7_parse_message+0xee/0x240 crypto/asymmetric_keys/pkcs7_parser.c:139 verify_pkcs7_signature+0x33/0x180 certs/system_keyring.c:216 pkcs7_preparse+0x41/0x70 crypto/asymmetric_keys/pkcs7_key_type.c:63 key_create_or_update+0x180/0x530 security/keys/key.c:855 SYSC_add_key security/keys/keyctl.c:122 [inline] SyS_add_key+0xbf/0x250 security/keys/keyctl.c:62 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4585c9 RSP: 002b:00007f10ed1f1bd8 EFLAGS: 00000216 ORIG_RAX: 00000000000000f8 RAX: ffffffffffffffda RBX: 00007f10ed1f2700 RCX: 00000000004585c9 RDX: 0000000020000000 RSI: 0000000020008ffb RDI: 0000000020008000 RBP: 0000000000000000 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000216 R12: 00007fff1b2260ae R13: 00007fff1b2260af R14: 00007f10ed1f2700 R15: 0000000000000000 Code: dd ca ff 48 8b 45 88 48 83 e8 01 4c 39 f0 0f 86 a8 07 00 00 e8 53 dd ca ff 49 8d 46 01 48 89 85 58 ff ff ff 48 8b 85 60 ff ff ff <42> 0f b6 0c 30 89 c8 88 8d 75 ff ff ff 83 e0 1f 89 8d 28 ff ff RIP: asn1_ber_decoder+0x17f/0xe60 lib/asn1_decoder.c:233 RSP: ffff9b6b37973c78 CR2: 0000000000000000 Fixes: 42d5ec27f873 ("X.509: Add an ASN.1 decoder") Reported-by: syzbot <syzkaller@googlegroups.com> Cc: <stable@vger.kernel.org> # v3.7+ Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
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dtc | ||
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genksyms | ||
kconfig | ||
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Makefile | -rw-r--r-- | 1.6 KB |
Makefile.asm-generic | -rw-r--r-- | 1.1 KB |
Makefile.build | -rw-r--r-- | 19.3 KB |
Makefile.clean | -rw-r--r-- | 3.0 KB |
Makefile.dtbinst | -rw-r--r-- | 1.1 KB |
Makefile.extrawarn | -rw-r--r-- | 2.6 KB |
Makefile.gcc-plugins | -rw-r--r-- | 3.6 KB |
Makefile.headersinst | -rw-r--r-- | 4.0 KB |
Makefile.help | -rw-r--r-- | 68 bytes |
Makefile.host | -rw-r--r-- | 6.7 KB |
Makefile.kasan | -rw-r--r-- | 1.0 KB |
Makefile.lib | -rw-r--r-- | 15.4 KB |
Makefile.modbuiltin | -rw-r--r-- | 1.8 KB |
Makefile.modinst | -rw-r--r-- | 1.3 KB |
Makefile.modpost | -rw-r--r-- | 5.5 KB |
Makefile.modsign | -rw-r--r-- | 1.0 KB |
Makefile.ubsan | -rw-r--r-- | 1.1 KB |
adjust_autoksyms.sh | -rwxr-xr-x | 2.8 KB |
asn1_compiler.c | -rw-r--r-- | 35.5 KB |
bloat-o-meter | -rwxr-xr-x | 2.2 KB |
bootgraph.pl | -rwxr-xr-x | 6.3 KB |
check_00index.sh | -rwxr-xr-x | 1.3 KB |
check_extable.sh | -rwxr-xr-x | 4.9 KB |
checkincludes.pl | -rwxr-xr-x | 1.9 KB |
checkkconfigsymbols.py | -rwxr-xr-x | 15.5 KB |
checkpatch.pl | -rwxr-xr-x | 187.8 KB |
checkstack.pl | -rwxr-xr-x | 5.5 KB |
checksyscalls.sh | -rwxr-xr-x | 5.7 KB |
checkversion.pl | -rwxr-xr-x | 1.9 KB |
cleanfile | -rwxr-xr-x | 3.5 KB |
cleanpatch | -rwxr-xr-x | 5.1 KB |
coccicheck | -rwxr-xr-x | 7.1 KB |
config | -rwxr-xr-x | 4.5 KB |
conmakehash.c | -rw-r--r-- | 6.0 KB |
const_structs.checkpatch | -rw-r--r-- | 964 bytes |
decode_stacktrace.sh | -rwxr-xr-x | 3.7 KB |
decodecode | -rwxr-xr-x | 2.2 KB |
depmod.sh | -rwxr-xr-x | 1.7 KB |
diffconfig | -rwxr-xr-x | 3.7 KB |
export_report.pl | -rwxr-xr-x | 4.5 KB |
extract-cert.c | -rw-r--r-- | 3.5 KB |
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extract-module-sig.pl | -rwxr-xr-x | 3.7 KB |
extract-sys-certs.pl | -rwxr-xr-x | 3.7 KB |
extract-vmlinux | -rwxr-xr-x | 1.6 KB |
extract_xc3028.pl | -rwxr-xr-x | 44.6 KB |
faddr2line | -rwxr-xr-x | 5.3 KB |
gcc-goto.sh | -rwxr-xr-x | 530 bytes |
gcc-ld | -rwxr-xr-x | 711 bytes |
gcc-plugin.sh | -rwxr-xr-x | 1.1 KB |
gcc-version.sh | -rwxr-xr-x | 857 bytes |
gcc-x86_32-has-stack-protector.sh | -rwxr-xr-x | 219 bytes |
gcc-x86_64-has-stack-protector.sh | -rwxr-xr-x | 244 bytes |
gen_initramfs_list.sh | -rwxr-xr-x | 8.0 KB |
get_dvb_firmware | -rwxr-xr-x | 25.2 KB |
get_maintainer.pl | -rwxr-xr-x | 60.1 KB |
gfp-translate | -rwxr-xr-x | 1.7 KB |
headerdep.pl | -rwxr-xr-x | 3.5 KB |
headers.sh | -rwxr-xr-x | 512 bytes |
headers_check.pl | -rwxr-xr-x | 3.7 KB |
headers_install.sh | -rwxr-xr-x | 1.3 KB |
insert-sys-cert.c | -rw-r--r-- | 8.9 KB |
kallsyms.c | -rw-r--r-- | 18.7 KB |
kernel-doc | -rwxr-xr-x | 91.8 KB |
ld-version.sh | -rwxr-xr-x | 269 bytes |
leaking_addresses.pl | -rwxr-xr-x | 6.6 KB |
link-vmlinux.sh | -rwxr-xr-x | 7.8 KB |
makelst | -rwxr-xr-x | 808 bytes |
markup_oops.pl | -rwxr-xr-x | 8.1 KB |
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mkmakefile | -rwxr-xr-x | 1.2 KB |
mksysmap | -rwxr-xr-x | 1.3 KB |
mkuboot.sh | -rwxr-xr-x | 414 bytes |
module-common.lds | -rw-r--r-- | 901 bytes |
namespace.pl | -rwxr-xr-x | 13.0 KB |
objdiff | -rwxr-xr-x | 2.8 KB |
parse-maintainers.pl | -rw-r--r-- | 2.8 KB |
patch-kernel | -rwxr-xr-x | 9.9 KB |
pnmtologo.c | -rw-r--r-- | 11.9 KB |
profile2linkerlist.pl | -rwxr-xr-x | 414 bytes |
prune-kernel | -rwxr-xr-x | 708 bytes |
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recordmcount.pl | -rwxr-xr-x | 18.0 KB |
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stackdelta | -rwxr-xr-x | 1.8 KB |
stackusage | -rwxr-xr-x | 794 bytes |
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ver_linux | -rwxr-xr-x | 2.9 KB |
xen-hypercalls.sh | -rw-r--r-- | 386 bytes |
xz_wrap.sh | -rwxr-xr-x | 562 bytes |
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