CVE-2022-50231

In the Linux kernel, the following vulnerability has been resolved:

crypto: arm64/poly1305 - fix a read out-of-bound

A kasan error was reported during fuzzing:

BUG: KASAN: slab-out-of-bounds in neon_poly1305_blocks.constprop.0+0x1b4/0x250 [poly1305_neon]

Read of size 4 at addr ffff0010e293f010 by task syz-executor.5/1646715

CPU: 4 PID: 1646715 Comm: syz-executor.5 Kdump: loaded Not tainted 5.10.0.aarch64 #1

Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.59 01/31/2019

Call trace:

dump_backtrace+0x0/0x394

show_stack+0x34/0x4c arch/arm64/kernel/stacktrace.c:196

__dump_stack lib/dump_stack.c:77 [inline]

dump_stack+0x158/0x1e4 lib/dump_stack.c:118

print_address_description.constprop.0+0x68/0x204 mm/kasan/report.c:387

__kasan_report+0xe0/0x140 mm/kasan/report.c:547

kasan_report+0x44/0xe0 mm/kasan/report.c:564

check_memory_region_inline mm/kasan/generic.c:187 [inline]

__asan_load4+0x94/0xd0 mm/kasan/generic.c:252

neon_poly1305_blocks.constprop.0+0x1b4/0x250 [poly1305_neon]

neon_poly1305_do_update+0x6c/0x15c [poly1305_neon]

neon_poly1305_update+0x9c/0x1c4 [poly1305_neon]

crypto_shash_update crypto/shash.c:131 [inline]

shash_finup_unaligned+0x84/0x15c crypto/shash.c:179

crypto_shash_finup+0x8c/0x140 crypto/shash.c:193

shash_digest_unaligned+0xb8/0xe4 crypto/shash.c:201

crypto_shash_digest+0xa4/0xfc crypto/shash.c:217

crypto_shash_tfm_digest+0xb4/0x150 crypto/shash.c:229

essiv_skcipher_setkey+0x164/0x200 [essiv]

crypto_skcipher_setkey+0xb0/0x160 crypto/skcipher.c:612

skcipher_setkey+0x3c/0x50 crypto/algif_skcipher.c:305

alg_setkey+0x114/0x2a0 crypto/af_alg.c:220

alg_setsockopt+0x19c/0x210 crypto/af_alg.c:253

__sys_setsockopt+0x190/0x2e0 net/socket.c:2123

__do_sys_setsockopt net/socket.c:2134 [inline]

__se_sys_setsockopt net/socket.c:2131 [inline]

__arm64_sys_setsockopt+0x78/0x94 net/socket.c:2131

__invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]

invoke_syscall+0x64/0x100 arch/arm64/kernel/syscall.c:48

el0_svc_common.constprop.0+0x220/0x230 arch/arm64/kernel/syscall.c:155

do_el0_svc+0xb4/0xd4 arch/arm64/kernel/syscall.c:217

el0_svc+0x24/0x3c arch/arm64/kernel/entry-common.c:353

el0_sync_handler+0x160/0x164 arch/arm64/kernel/entry-common.c:369

el0_sync+0x160/0x180 arch/arm64/kernel/entry.S:683

This error can be reproduced by the following code compiled as ko on a

system with kasan enabled:

#include <linux/module.h>

#include <linux/crypto.h>

#include <crypto/hash.h>

#include <crypto/poly1305.h>

char test_data[] = "\x00\x01\x02\x03\x04\x05\x06\x07"

"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"

"\x10\x11\x12\x13\x14\x15\x16\x17"

"\x18\x19\x1a\x1b\x1c\x1d\x1e";

int init(void)

{

struct crypto_shash *tfm = NULL;

char *data = NULL, *out = NULL;

tfm = crypto_alloc_shash("poly1305", 0, 0);

data = kmalloc(POLY1305_KEY_SIZE - 1, GFP_KERNEL);

out = kmalloc(POLY1305_DIGEST_SIZE, GFP_KERNEL);

memcpy(data, test_data, POLY1305_KEY_SIZE - 1);

crypto_shash_tfm_digest(tfm, data, POLY1305_KEY_SIZE - 1, out);

kfree(data);

kfree(out);

return 0;

}

void deinit(void)

{

}

module_init(init)

module_exit(deinit)

MODULE_LICENSE("GPL");

The root cause of the bug sits in neon_poly1305_blocks. The logic

neon_poly1305_blocks() performed is that if it was called with both s[]

and r[] uninitialized, it will first try to initialize them with the

data from the first "block" that it believed to be 32 bytes in length.

First 16 bytes are used as the key and the next 16 bytes for s[]. This

would lead to the aforementioned read out-of-bound. However, after

calling poly1305_init_arch(), only 16 bytes were deducted from the input

and s[] is initialized yet again with the following 16 bytes. The second

initialization of s[] is certainly redundent which indicates that the

first initialization should be for r[] only.

This patch fixes the issue by calling poly1305_init_arm64() instead o

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