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, 498 insertions, 0 deletions

diff --git a/drivers/crypto/qce/sha.c b/drivers/crypto/qce/sha.c
new file mode 100644
index 000000000..eb8a5b0c4
--- /dev/null
+++ b/drivers/crypto/qce/sha.c
@@ -0,0 +1,498 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2010-2014, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/interrupt.h>
+#include <linux/string.h>
+#include <crypto/internal/hash.h>
+
+#include "common.h"
+#include "core.h"
+#include "sha.h"
+
+struct qce_sha_saved_state {
+	u8 pending_buf[QCE_SHA_MAX_BLOCKSIZE];
+	u8 partial_digest[QCE_SHA_MAX_DIGESTSIZE];
+	__be32 byte_count[2];
+	unsigned int pending_buflen;
+	unsigned int flags;
+	u64 count;
+	bool first_blk;
+};
+
+static LIST_HEAD(ahash_algs);
+
+static const u32 std_iv_sha256[SHA256_DIGEST_SIZE / sizeof(u32)] = {
+	SHA256_H0, SHA256_H1, SHA256_H2, SHA256_H3,
+	SHA256_H4, SHA256_H5, SHA256_H6, SHA256_H7
+};
+
+static void qce_ahash_done(void *data)
+{
+	struct crypto_async_request *async_req = data;
+	struct ahash_request *req = ahash_request_cast(async_req);
+	struct crypto_ahash *ahash = crypto_ahash_reqtfm(req);
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	struct qce_alg_template *tmpl = to_ahash_tmpl(async_req->tfm);
+	struct qce_device *qce = tmpl->qce;
+	struct qce_result_dump *result = qce->dma.result_buf;
+	unsigned int digestsize = crypto_ahash_digestsize(ahash);
+	int error;
+	u32 status;
+
+	error = qce_dma_terminate_all(&qce->dma);
+	if (error)
+		dev_dbg(qce->dev, "ahash dma termination error (%d)\n", error);
+
+	dma_unmap_sg(qce->dev, req->src, rctx->src_nents, DMA_TO_DEVICE);
+	dma_unmap_sg(qce->dev, &rctx->result_sg, 1, DMA_FROM_DEVICE);
+
+	memcpy(rctx->digest, result->auth_iv, digestsize);
+	if (req->result && rctx->last_blk)
+		memcpy(req->result, result->auth_iv, digestsize);
+
+	rctx->byte_count[0] = cpu_to_be32(result->auth_byte_count[0]);
+	rctx->byte_count[1] = cpu_to_be32(result->auth_byte_count[1]);
+
+	error = qce_check_status(qce, &status);
+	if (error < 0)
+		dev_dbg(qce->dev, "ahash operation error (%x)\n", status);
+
+	req->src = rctx->src_orig;
+	req->nbytes = rctx->nbytes_orig;
+	rctx->last_blk = false;
+	rctx->first_blk = false;
+
+	qce->async_req_done(tmpl->qce, error);
+}
+
+static int qce_ahash_async_req_handle(struct crypto_async_request *async_req)
+{
+	struct ahash_request *req = ahash_request_cast(async_req);
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	struct qce_sha_ctx *ctx = crypto_tfm_ctx(async_req->tfm);
+	struct qce_alg_template *tmpl = to_ahash_tmpl(async_req->tfm);
+	struct qce_device *qce = tmpl->qce;
+	unsigned long flags = rctx->flags;
+	int ret;
+
+	if (IS_SHA_HMAC(flags)) {
+		rctx->authkey = ctx->authkey;
+		rctx->authklen = QCE_SHA_HMAC_KEY_SIZE;
+	} else if (IS_CMAC(flags)) {
+		rctx->authkey = ctx->authkey;
+		rctx->authklen = AES_KEYSIZE_128;
+	}
+
+	rctx->src_nents = sg_nents_for_len(req->src, req->nbytes);
+	if (rctx->src_nents < 0) {
+		dev_err(qce->dev, "Invalid numbers of src SG.\n");
+		return rctx->src_nents;
+	}
+
+	ret = dma_map_sg(qce->dev, req->src, rctx->src_nents, DMA_TO_DEVICE);
+	if (!ret)
+		return -EIO;
+
+	sg_init_one(&rctx->result_sg, qce->dma.result_buf, QCE_RESULT_BUF_SZ);
+
+	ret = dma_map_sg(qce->dev, &rctx->result_sg, 1, DMA_FROM_DEVICE);
+	if (!ret) {
+		ret = -EIO;
+		goto error_unmap_src;
+	}
+
+	ret = qce_dma_prep_sgs(&qce->dma, req->src, rctx->src_nents,
+			       &rctx->result_sg, 1, qce_ahash_done, async_req);
+	if (ret)
+		goto error_unmap_dst;
+
+	qce_dma_issue_pending(&qce->dma);
+
+	ret = qce_start(async_req, tmpl->crypto_alg_type);
+	if (ret)
+		goto error_terminate;
+
+	return 0;
+
+error_terminate:
+	qce_dma_terminate_all(&qce->dma);
+error_unmap_dst:
+	dma_unmap_sg(qce->dev, &rctx->result_sg, 1, DMA_FROM_DEVICE);
+error_unmap_src:
+	dma_unmap_sg(qce->dev, req->src, rctx->src_nents, DMA_TO_DEVICE);
+	return ret;
+}
+
+static int qce_ahash_init(struct ahash_request *req)
+{
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	struct qce_alg_template *tmpl = to_ahash_tmpl(req->base.tfm);
+	const u32 *std_iv = tmpl->std_iv;
+
+	memset(rctx, 0, sizeof(*rctx));
+	rctx->first_blk = true;
+	rctx->last_blk = false;
+	rctx->flags = tmpl->alg_flags;
+	memcpy(rctx->digest, std_iv, sizeof(rctx->digest));
+
+	return 0;
+}
+
+static int qce_ahash_export(struct ahash_request *req, void *out)
+{
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	struct qce_sha_saved_state *export_state = out;
+
+	memcpy(export_state->pending_buf, rctx->buf, rctx->buflen);
+	memcpy(export_state->partial_digest, rctx->digest, sizeof(rctx->digest));
+	export_state->byte_count[0] = rctx->byte_count[0];
+	export_state->byte_count[1] = rctx->byte_count[1];
+	export_state->pending_buflen = rctx->buflen;
+	export_state->count = rctx->count;
+	export_state->first_blk = rctx->first_blk;
+	export_state->flags = rctx->flags;
+
+	return 0;
+}
+
+static int qce_ahash_import(struct ahash_request *req, const void *in)
+{
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	const struct qce_sha_saved_state *import_state = in;
+
+	memset(rctx, 0, sizeof(*rctx));
+	rctx->count = import_state->count;
+	rctx->buflen = import_state->pending_buflen;
+	rctx->first_blk = import_state->first_blk;
+	rctx->flags = import_state->flags;
+	rctx->byte_count[0] = import_state->byte_count[0];
+	rctx->byte_count[1] = import_state->byte_count[1];
+	memcpy(rctx->buf, import_state->pending_buf, rctx->buflen);
+	memcpy(rctx->digest, import_state->partial_digest, sizeof(rctx->digest));
+
+	return 0;
+}
+
+static int qce_ahash_update(struct ahash_request *req)
+{
+	struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	struct qce_alg_template *tmpl = to_ahash_tmpl(req->base.tfm);
+	struct qce_device *qce = tmpl->qce;
+	unsigned int total;
+	unsigned int hash_later;
+	unsigned int blocksize;
+
+	blocksize = crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
+	rctx->count += req->nbytes;
+
+	/* check for buffer from previous updates and append it */
+	total = req->nbytes + rctx->buflen;
+
+	if (total <= blocksize) {
+		scatterwalk_map_and_copy(rctx->buf + rctx->buflen, req->src,
+					 0, req->nbytes, 0);
+		rctx->buflen += req->nbytes;
+		return 0;
+	}
+
+	/* save the original req structure fields */
+	rctx->src_orig = req->src;
+	rctx->nbytes_orig = req->nbytes;
+
+	/*
+	 * if we have data from previous update copy them on buffer. The old
+	 * data will be combined with current request bytes.
+	 */
+	if (rctx->buflen)
+		memcpy(rctx->tmpbuf, rctx->buf, rctx->buflen);
+
+	/* calculate how many bytes will be hashed later */
+	hash_later = total % blocksize;
+
+	/*
+	 * At this point, there is more than one block size of data.  If
+	 * the available data to transfer is exactly a multiple of block
+	 * size, save the last block to be transferred in qce_ahash_final
+	 * (with the last block bit set) if this is indeed the end of data
+	 * stream. If not this saved block will be transferred as part of
+	 * next update. If this block is not held back and if this is
+	 * indeed the end of data stream, the digest obtained will be wrong
+	 * since qce_ahash_final will see that rctx->buflen is 0 and return
+	 * doing nothing which in turn means that a digest will not be
+	 * copied to the destination result buffer.  qce_ahash_final cannot
+	 * be made to alter this behavior and allowed to proceed if
+	 * rctx->buflen is 0 because the crypto engine BAM does not allow
+	 * for zero length transfers.
+	 */
+	if (!hash_later)
+		hash_later = blocksize;
+
+	scatterwalk_map_and_copy(rctx->buf, req->src, req->nbytes - hash_later,
+				 hash_later, 0);
+
+	if (rctx->buflen) {
+		sg_init_table(rctx->sg, 2);
+		sg_set_buf(rctx->sg, rctx->tmpbuf, rctx->buflen);
+		sg_chain(rctx->sg, 2, req->src);
+		req->src = rctx->sg;
+	}
+
+	/* hash only complete blocks */
+	req->nbytes = total - hash_later;
+	rctx->buflen = hash_later;
+
+	return qce->async_req_enqueue(tmpl->qce, &req->base);
+}
+
+static int qce_ahash_final(struct ahash_request *req)
+{
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	struct qce_alg_template *tmpl = to_ahash_tmpl(req->base.tfm);
+	struct qce_device *qce = tmpl->qce;
+
+	if (!rctx->buflen) {
+		if (tmpl->hash_zero)
+			memcpy(req->result, tmpl->hash_zero,
+					tmpl->alg.ahash.halg.digestsize);
+		return 0;
+	}
+
+	rctx->last_blk = true;
+
+	rctx->src_orig = req->src;
+	rctx->nbytes_orig = req->nbytes;
+
+	memcpy(rctx->tmpbuf, rctx->buf, rctx->buflen);
+	sg_init_one(rctx->sg, rctx->tmpbuf, rctx->buflen);
+
+	req->src = rctx->sg;
+	req->nbytes = rctx->buflen;
+
+	return qce->async_req_enqueue(tmpl->qce, &req->base);
+}
+
+static int qce_ahash_digest(struct ahash_request *req)
+{
+	struct qce_sha_reqctx *rctx = ahash_request_ctx_dma(req);
+	struct qce_alg_template *tmpl = to_ahash_tmpl(req->base.tfm);
+	struct qce_device *qce = tmpl->qce;
+	int ret;
+
+	ret = qce_ahash_init(req);
+	if (ret)
+		return ret;
+
+	rctx->src_orig = req->src;
+	rctx->nbytes_orig = req->nbytes;
+	rctx->first_blk = true;
+	rctx->last_blk = true;
+
+	if (!rctx->nbytes_orig) {
+		if (tmpl->hash_zero)
+			memcpy(req->result, tmpl->hash_zero,
+					tmpl->alg.ahash.halg.digestsize);
+		return 0;
+	}
+
+	return qce->async_req_enqueue(tmpl->qce, &req->base);
+}
+
+static int qce_ahash_hmac_setkey(struct crypto_ahash *tfm, const u8 *key,
+				 unsigned int keylen)
+{
+	unsigned int digestsize = crypto_ahash_digestsize(tfm);
+	struct qce_sha_ctx *ctx = crypto_tfm_ctx(&tfm->base);
+	struct crypto_wait wait;
+	struct ahash_request *req;
+	struct scatterlist sg;
+	unsigned int blocksize;
+	struct crypto_ahash *ahash_tfm;
+	u8 *buf;
+	int ret;
+	const char *alg_name;
+
+	blocksize = crypto_tfm_alg_blocksize(crypto_ahash_tfm(tfm));
+	memset(ctx->authkey, 0, sizeof(ctx->authkey));
+
+	if (keylen <= blocksize) {
+		memcpy(ctx->authkey, key, keylen);
+		return 0;
+	}
+
+	if (digestsize == SHA256_DIGEST_SIZE)
+		alg_name = "sha256-qce";
+	else
+		return -EINVAL;
+
+	ahash_tfm = crypto_alloc_ahash(alg_name, 0, 0);
+	if (IS_ERR(ahash_tfm))
+		return PTR_ERR(ahash_tfm);
+
+	req = ahash_request_alloc(ahash_tfm, GFP_KERNEL);
+	if (!req) {
+		ret = -ENOMEM;
+		goto err_free_ahash;
+	}
+
+	crypto_init_wait(&wait);
+	ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+				   crypto_req_done, &wait);
+	crypto_ahash_clear_flags(ahash_tfm, ~0);
+
+	buf = kzalloc(keylen + QCE_MAX_ALIGN_SIZE, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto err_free_req;
+	}
+
+	memcpy(buf, key, keylen);
+	sg_init_one(&sg, buf, keylen);
+	ahash_request_set_crypt(req, &sg, ctx->authkey, keylen);
+
+	ret = crypto_wait_req(crypto_ahash_digest(req), &wait);
+
+	kfree(buf);
+err_free_req:
+	ahash_request_free(req);
+err_free_ahash:
+	crypto_free_ahash(ahash_tfm);
+	return ret;
+}
+
+static int qce_ahash_cra_init(struct crypto_tfm *tfm)
+{
+	struct crypto_ahash *ahash = __crypto_ahash_cast(tfm);
+	struct qce_sha_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	crypto_ahash_set_reqsize_dma(ahash, sizeof(struct qce_sha_reqctx));
+	memset(ctx, 0, sizeof(*ctx));
+	return 0;
+}
+
+struct qce_ahash_def {
+	unsigned long flags;
+	const char *name;
+	const char *drv_name;
+	unsigned int digestsize;
+	unsigned int blocksize;
+	unsigned int statesize;
+	const u32 *std_iv;
+};
+
+static const struct qce_ahash_def ahash_def[] = {
+	{
+		.flags		= QCE_HASH_SHA256,
+		.name		= "sha256",
+		.drv_name	= "sha256-qce",
+		.digestsize	= SHA256_DIGEST_SIZE,
+		.blocksize	= SHA256_BLOCK_SIZE,
+		.statesize	= sizeof(struct qce_sha_saved_state),
+		.std_iv		= std_iv_sha256,
+	},
+	{
+		.flags		= QCE_HASH_SHA256_HMAC,
+		.name		= "hmac(sha256)",
+		.drv_name	= "hmac-sha256-qce",
+		.digestsize	= SHA256_DIGEST_SIZE,
+		.blocksize	= SHA256_BLOCK_SIZE,
+		.statesize	= sizeof(struct qce_sha_saved_state),
+		.std_iv		= std_iv_sha256,
+	},
+};
+
+static int qce_ahash_register_one(const struct qce_ahash_def *def,
+				  struct qce_device *qce)
+{
+	struct qce_alg_template *tmpl;
+	struct ahash_alg *alg;
+	struct crypto_alg *base;
+	int ret;
+
+	tmpl = kzalloc_obj(*tmpl);
+	if (!tmpl)
+		return -ENOMEM;
+
+	tmpl->std_iv = def->std_iv;
+
+	alg = &tmpl->alg.ahash;
+	alg->init = qce_ahash_init;
+	alg->update = qce_ahash_update;
+	alg->final = qce_ahash_final;
+	alg->digest = qce_ahash_digest;
+	alg->export = qce_ahash_export;
+	alg->import = qce_ahash_import;
+	if (IS_SHA_HMAC(def->flags))
+		alg->setkey = qce_ahash_hmac_setkey;
+	alg->halg.digestsize = def->digestsize;
+	alg->halg.statesize = def->statesize;
+
+	if (IS_SHA256(def->flags))
+		tmpl->hash_zero = sha256_zero_message_hash;
+
+	base = &alg->halg.base;
+	base->cra_blocksize = def->blocksize;
+	base->cra_priority = 175;
+	base->cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_KERN_DRIVER_ONLY;
+	base->cra_ctxsize = sizeof(struct qce_sha_ctx);
+	base->cra_alignmask = 0;
+	base->cra_module = THIS_MODULE;
+	base->cra_init = qce_ahash_cra_init;
+
+	strscpy(base->cra_name, def->name);
+	strscpy(base->cra_driver_name, def->drv_name);
+
+	INIT_LIST_HEAD(&tmpl->entry);
+	tmpl->crypto_alg_type = CRYPTO_ALG_TYPE_AHASH;
+	tmpl->alg_flags = def->flags;
+	tmpl->qce = qce;
+
+	ret = crypto_register_ahash(alg);
+	if (ret) {
+		dev_err(qce->dev, "%s registration failed\n", base->cra_name);
+		kfree(tmpl);
+		return ret;
+	}
+
+	list_add_tail(&tmpl->entry, &ahash_algs);
+	dev_dbg(qce->dev, "%s is registered\n", base->cra_name);
+	return 0;
+}
+
+static void qce_ahash_unregister(struct qce_device *qce)
+{
+	struct qce_alg_template *tmpl, *n;
+
+	list_for_each_entry_safe(tmpl, n, &ahash_algs, entry) {
+		crypto_unregister_ahash(&tmpl->alg.ahash);
+		list_del(&tmpl->entry);
+		kfree(tmpl);
+	}
+}
+
+static int qce_ahash_register(struct qce_device *qce)
+{
+	int ret, i;
+
+	for (i = 0; i < ARRAY_SIZE(ahash_def); i++) {
+		ret = qce_ahash_register_one(&ahash_def[i], qce);
+		if (ret)
+			goto err;
+	}
+
+	return 0;
+err:
+	qce_ahash_unregister(qce);
+	return ret;
+}
+
+const struct qce_algo_ops ahash_ops = {
+	.type = CRYPTO_ALG_TYPE_AHASH,
+	.register_algs = qce_ahash_register,
+	.unregister_algs = qce_ahash_unregister,
+	.async_req_handle = qce_ahash_async_req_handle,
+};