x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 436 insertions, 0 deletions

diff --git a/drivers/crypto/geode-aes.c b/drivers/crypto/geode-aes.c
new file mode 100644
index 000000000..d933f26ae
--- /dev/null
+++ b/drivers/crypto/geode-aes.c
@@ -0,0 +1,436 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+ /* Copyright (C) 2004-2006, Advanced Micro Devices, Inc.
+  */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/pci.h>
+#include <linux/pci_ids.h>
+#include <linux/crypto.h>
+#include <linux/spinlock.h>
+#include <crypto/algapi.h>
+#include <crypto/aes.h>
+#include <crypto/internal/cipher.h>
+#include <crypto/internal/skcipher.h>
+
+#include <linux/io.h>
+#include <linux/delay.h>
+
+#include "geode-aes.h"
+
+/* Static structures */
+
+static void __iomem *_iobase;
+static DEFINE_SPINLOCK(lock);
+
+/* Write a 128 bit field (either a writable key or IV) */
+static inline void
+_writefield(u32 offset, const void *value)
+{
+	int i;
+
+	for (i = 0; i < 4; i++)
+		iowrite32(((const u32 *) value)[i], _iobase + offset + (i * 4));
+}
+
+/* Read a 128 bit field (either a writable key or IV) */
+static inline void
+_readfield(u32 offset, void *value)
+{
+	int i;
+
+	for (i = 0; i < 4; i++)
+		((u32 *) value)[i] = ioread32(_iobase + offset + (i * 4));
+}
+
+static int
+do_crypt(const void *src, void *dst, u32 len, u32 flags)
+{
+	u32 status;
+	u32 counter = AES_OP_TIMEOUT;
+
+	iowrite32(virt_to_phys((void *)src), _iobase + AES_SOURCEA_REG);
+	iowrite32(virt_to_phys(dst), _iobase + AES_DSTA_REG);
+	iowrite32(len,  _iobase + AES_LENA_REG);
+
+	/* Start the operation */
+	iowrite32(AES_CTRL_START | flags, _iobase + AES_CTRLA_REG);
+
+	do {
+		status = ioread32(_iobase + AES_INTR_REG);
+		cpu_relax();
+	} while (!(status & AES_INTRA_PENDING) && --counter);
+
+	/* Clear the event */
+	iowrite32((status & 0xFF) | AES_INTRA_PENDING, _iobase + AES_INTR_REG);
+	return counter ? 0 : 1;
+}
+
+static void
+geode_aes_crypt(const struct geode_aes_tfm_ctx *tctx, const void *src,
+		void *dst, u32 len, u8 *iv, int mode, int dir)
+{
+	u32 flags = 0;
+	unsigned long iflags;
+	int ret;
+
+	/* If the source and destination is the same, then
+	 * we need to turn on the coherent flags, otherwise
+	 * we don't need to worry
+	 */
+
+	flags |= (AES_CTRL_DCA | AES_CTRL_SCA);
+
+	if (dir == AES_DIR_ENCRYPT)
+		flags |= AES_CTRL_ENCRYPT;
+
+	/* Start the critical section */
+
+	spin_lock_irqsave(&lock, iflags);
+
+	if (mode == AES_MODE_CBC) {
+		flags |= AES_CTRL_CBC;
+		_writefield(AES_WRITEIV0_REG, iv);
+	}
+
+	flags |= AES_CTRL_WRKEY;
+	_writefield(AES_WRITEKEY0_REG, tctx->key);
+
+	ret = do_crypt(src, dst, len, flags);
+	BUG_ON(ret);
+
+	if (mode == AES_MODE_CBC)
+		_readfield(AES_WRITEIV0_REG, iv);
+
+	spin_unlock_irqrestore(&lock, iflags);
+}
+
+/* CRYPTO-API Functions */
+
+static int geode_setkey_cip(struct crypto_tfm *tfm, const u8 *key,
+		unsigned int len)
+{
+	struct geode_aes_tfm_ctx *tctx = crypto_tfm_ctx(tfm);
+
+	tctx->keylen = len;
+
+	if (len == AES_KEYSIZE_128) {
+		memcpy(tctx->key, key, len);
+		return 0;
+	}
+
+	if (len != AES_KEYSIZE_192 && len != AES_KEYSIZE_256)
+		/* not supported at all */
+		return -EINVAL;
+
+	/*
+	 * The requested key size is not supported by HW, do a fallback
+	 */
+	tctx->fallback.cip->base.crt_flags &= ~CRYPTO_TFM_REQ_MASK;
+	tctx->fallback.cip->base.crt_flags |=
+		(tfm->crt_flags & CRYPTO_TFM_REQ_MASK);
+
+	return crypto_cipher_setkey(tctx->fallback.cip, key, len);
+}
+
+static int geode_setkey_skcipher(struct crypto_skcipher *tfm, const u8 *key,
+				 unsigned int len)
+{
+	struct geode_aes_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
+
+	tctx->keylen = len;
+
+	if (len == AES_KEYSIZE_128) {
+		memcpy(tctx->key, key, len);
+		return 0;
+	}
+
+	if (len != AES_KEYSIZE_192 && len != AES_KEYSIZE_256)
+		/* not supported at all */
+		return -EINVAL;
+
+	/*
+	 * The requested key size is not supported by HW, do a fallback
+	 */
+	crypto_skcipher_clear_flags(tctx->fallback.skcipher,
+				    CRYPTO_TFM_REQ_MASK);
+	crypto_skcipher_set_flags(tctx->fallback.skcipher,
+				  crypto_skcipher_get_flags(tfm) &
+				  CRYPTO_TFM_REQ_MASK);
+	return crypto_skcipher_setkey(tctx->fallback.skcipher, key, len);
+}
+
+static void
+geode_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+{
+	const struct geode_aes_tfm_ctx *tctx = crypto_tfm_ctx(tfm);
+
+	if (unlikely(tctx->keylen != AES_KEYSIZE_128)) {
+		crypto_cipher_encrypt_one(tctx->fallback.cip, out, in);
+		return;
+	}
+
+	geode_aes_crypt(tctx, in, out, AES_BLOCK_SIZE, NULL,
+			AES_MODE_ECB, AES_DIR_ENCRYPT);
+}
+
+
+static void
+geode_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+{
+	const struct geode_aes_tfm_ctx *tctx = crypto_tfm_ctx(tfm);
+
+	if (unlikely(tctx->keylen != AES_KEYSIZE_128)) {
+		crypto_cipher_decrypt_one(tctx->fallback.cip, out, in);
+		return;
+	}
+
+	geode_aes_crypt(tctx, in, out, AES_BLOCK_SIZE, NULL,
+			AES_MODE_ECB, AES_DIR_DECRYPT);
+}
+
+static int fallback_init_cip(struct crypto_tfm *tfm)
+{
+	const char *name = crypto_tfm_alg_name(tfm);
+	struct geode_aes_tfm_ctx *tctx = crypto_tfm_ctx(tfm);
+
+	tctx->fallback.cip = crypto_alloc_cipher(name, 0,
+						 CRYPTO_ALG_NEED_FALLBACK);
+
+	if (IS_ERR(tctx->fallback.cip)) {
+		printk(KERN_ERR "Error allocating fallback algo %s\n", name);
+		return PTR_ERR(tctx->fallback.cip);
+	}
+
+	return 0;
+}
+
+static void fallback_exit_cip(struct crypto_tfm *tfm)
+{
+	struct geode_aes_tfm_ctx *tctx = crypto_tfm_ctx(tfm);
+
+	crypto_free_cipher(tctx->fallback.cip);
+}
+
+static struct crypto_alg geode_alg = {
+	.cra_name			=	"aes",
+	.cra_driver_name	=	"geode-aes",
+	.cra_priority		=	300,
+	.cra_alignmask		=	15,
+	.cra_flags			=	CRYPTO_ALG_TYPE_CIPHER |
+							CRYPTO_ALG_NEED_FALLBACK,
+	.cra_init			=	fallback_init_cip,
+	.cra_exit			=	fallback_exit_cip,
+	.cra_blocksize		=	AES_BLOCK_SIZE,
+	.cra_ctxsize		=	sizeof(struct geode_aes_tfm_ctx),
+	.cra_module			=	THIS_MODULE,
+	.cra_u				=	{
+		.cipher	=	{
+			.cia_min_keysize	=	AES_MIN_KEY_SIZE,
+			.cia_max_keysize	=	AES_MAX_KEY_SIZE,
+			.cia_setkey			=	geode_setkey_cip,
+			.cia_encrypt		=	geode_encrypt,
+			.cia_decrypt		=	geode_decrypt
+		}
+	}
+};
+
+static int geode_init_skcipher(struct crypto_skcipher *tfm)
+{
+	const char *name = crypto_tfm_alg_name(&tfm->base);
+	struct geode_aes_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
+
+	tctx->fallback.skcipher =
+		crypto_alloc_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK |
+				      CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tctx->fallback.skcipher)) {
+		printk(KERN_ERR "Error allocating fallback algo %s\n", name);
+		return PTR_ERR(tctx->fallback.skcipher);
+	}
+
+	crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
+				    crypto_skcipher_reqsize(tctx->fallback.skcipher));
+	return 0;
+}
+
+static void geode_exit_skcipher(struct crypto_skcipher *tfm)
+{
+	struct geode_aes_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
+
+	crypto_free_skcipher(tctx->fallback.skcipher);
+}
+
+static int geode_skcipher_crypt(struct skcipher_request *req, int mode, int dir)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	const struct geode_aes_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
+	struct skcipher_walk walk;
+	unsigned int nbytes;
+	int err;
+
+	if (unlikely(tctx->keylen != AES_KEYSIZE_128)) {
+		struct skcipher_request *subreq = skcipher_request_ctx(req);
+
+		*subreq = *req;
+		skcipher_request_set_tfm(subreq, tctx->fallback.skcipher);
+		if (dir == AES_DIR_DECRYPT)
+			return crypto_skcipher_decrypt(subreq);
+		else
+			return crypto_skcipher_encrypt(subreq);
+	}
+
+	err = skcipher_walk_virt(&walk, req, false);
+
+	while ((nbytes = walk.nbytes) != 0) {
+		geode_aes_crypt(tctx, walk.src.virt.addr, walk.dst.virt.addr,
+				round_down(nbytes, AES_BLOCK_SIZE),
+				walk.iv, mode, dir);
+		err = skcipher_walk_done(&walk, nbytes % AES_BLOCK_SIZE);
+	}
+
+	return err;
+}
+
+static int geode_cbc_encrypt(struct skcipher_request *req)
+{
+	return geode_skcipher_crypt(req, AES_MODE_CBC, AES_DIR_ENCRYPT);
+}
+
+static int geode_cbc_decrypt(struct skcipher_request *req)
+{
+	return geode_skcipher_crypt(req, AES_MODE_CBC, AES_DIR_DECRYPT);
+}
+
+static int geode_ecb_encrypt(struct skcipher_request *req)
+{
+	return geode_skcipher_crypt(req, AES_MODE_ECB, AES_DIR_ENCRYPT);
+}
+
+static int geode_ecb_decrypt(struct skcipher_request *req)
+{
+	return geode_skcipher_crypt(req, AES_MODE_ECB, AES_DIR_DECRYPT);
+}
+
+static struct skcipher_alg geode_skcipher_algs[] = {
+	{
+		.base.cra_name		= "cbc(aes)",
+		.base.cra_driver_name	= "cbc-aes-geode",
+		.base.cra_priority	= 400,
+		.base.cra_flags		= CRYPTO_ALG_KERN_DRIVER_ONLY |
+					  CRYPTO_ALG_NEED_FALLBACK,
+		.base.cra_blocksize	= AES_BLOCK_SIZE,
+		.base.cra_ctxsize	= sizeof(struct geode_aes_tfm_ctx),
+		.base.cra_alignmask	= 15,
+		.base.cra_module	= THIS_MODULE,
+		.init			= geode_init_skcipher,
+		.exit			= geode_exit_skcipher,
+		.setkey			= geode_setkey_skcipher,
+		.encrypt		= geode_cbc_encrypt,
+		.decrypt		= geode_cbc_decrypt,
+		.min_keysize		= AES_MIN_KEY_SIZE,
+		.max_keysize		= AES_MAX_KEY_SIZE,
+		.ivsize			= AES_BLOCK_SIZE,
+	}, {
+		.base.cra_name		= "ecb(aes)",
+		.base.cra_driver_name	= "ecb-aes-geode",
+		.base.cra_priority	= 400,
+		.base.cra_flags		= CRYPTO_ALG_KERN_DRIVER_ONLY |
+					  CRYPTO_ALG_NEED_FALLBACK,
+		.base.cra_blocksize	= AES_BLOCK_SIZE,
+		.base.cra_ctxsize	= sizeof(struct geode_aes_tfm_ctx),
+		.base.cra_alignmask	= 15,
+		.base.cra_module	= THIS_MODULE,
+		.init			= geode_init_skcipher,
+		.exit			= geode_exit_skcipher,
+		.setkey			= geode_setkey_skcipher,
+		.encrypt		= geode_ecb_encrypt,
+		.decrypt		= geode_ecb_decrypt,
+		.min_keysize		= AES_MIN_KEY_SIZE,
+		.max_keysize		= AES_MAX_KEY_SIZE,
+	},
+};
+
+static void geode_aes_remove(struct pci_dev *dev)
+{
+	crypto_unregister_alg(&geode_alg);
+	crypto_unregister_skciphers(geode_skcipher_algs,
+				    ARRAY_SIZE(geode_skcipher_algs));
+
+	pci_iounmap(dev, _iobase);
+	_iobase = NULL;
+
+	pci_release_regions(dev);
+	pci_disable_device(dev);
+}
+
+
+static int geode_aes_probe(struct pci_dev *dev, const struct pci_device_id *id)
+{
+	int ret;
+
+	ret = pci_enable_device(dev);
+	if (ret)
+		return ret;
+
+	ret = pci_request_regions(dev, "geode-aes");
+	if (ret)
+		goto eenable;
+
+	_iobase = pci_iomap(dev, 0, 0);
+
+	if (_iobase == NULL) {
+		ret = -ENOMEM;
+		goto erequest;
+	}
+
+	/* Clear any pending activity */
+	iowrite32(AES_INTR_PENDING | AES_INTR_MASK, _iobase + AES_INTR_REG);
+
+	ret = crypto_register_alg(&geode_alg);
+	if (ret)
+		goto eiomap;
+
+	ret = crypto_register_skciphers(geode_skcipher_algs,
+					ARRAY_SIZE(geode_skcipher_algs));
+	if (ret)
+		goto ealg;
+
+	dev_notice(&dev->dev, "GEODE AES engine enabled.\n");
+	return 0;
+
+ ealg:
+	crypto_unregister_alg(&geode_alg);
+
+ eiomap:
+	pci_iounmap(dev, _iobase);
+
+ erequest:
+	pci_release_regions(dev);
+
+ eenable:
+	pci_disable_device(dev);
+
+	dev_err(&dev->dev, "GEODE AES initialization failed.\n");
+	return ret;
+}
+
+static struct pci_device_id geode_aes_tbl[] = {
+	{ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_LX_AES), },
+	{ 0, }
+};
+
+MODULE_DEVICE_TABLE(pci, geode_aes_tbl);
+
+static struct pci_driver geode_aes_driver = {
+	.name = "Geode LX AES",
+	.id_table = geode_aes_tbl,
+	.probe = geode_aes_probe,
+	.remove = geode_aes_remove,
+};
+
+module_pci_driver(geode_aes_driver);
+
+MODULE_AUTHOR("Advanced Micro Devices, Inc.");
+MODULE_DESCRIPTION("Geode LX Hardware AES driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("CRYPTO_INTERNAL");