Headline
CVE-2021-3744: oss-sec: Disclosure: CVE-2021-3744: crypto: ccp
A memory leak flaw was found in the Linux kernel in the ccp_run_aes_gcm_cmd() function in drivers/crypto/ccp/ccp-ops.c, which allows attackers to cause a denial of service (memory consumption). This vulnerability is similar with the older CVE-2019-18808.
Disclosure: CVE-2021-3744: crypto: ccp - fix resource leaks in ccp_run_aes_gcm_cmd()
From: Marcus Meissner <meissner () suse de>
Date: Tue, 14 Sep 2021 17:29:11 +0200
Hi,
CVE-2021-3744: crypto: ccp - fix resource leaks in ccp_run_aes_gcm_cmd()
This was reported by Tencent researcher <minihanshen () tencent com> to linux-distros, with disclosure date agreed to September 6th.
It was not followed up by timely disclosure so far, also everyone in the thread went silent for unknown reasons, even with 3 seperate reminders to publish.
As its now 1 week after the proposed embargoe end and has also expired the maximum 14 days embargo timeline, the linux-distros team publishes it to oss-security.
I am quoting the original report email, and the bugfix email from Dan Carpenter for Linux security.
Ciao, Marcus
Hello,
We found a vulnerability similar with CVE-2019-18808(https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-18808) which could allows attackers to cause a denial of service (memory consumption). Next is our analysis.
The vulnerability also appared on ccp_run_aes_gcm_cmd() funciton in driver in the Linux kernel through 5.14. // CODE-1 ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd) { struct ccp_aes_engine *aes = &cmd->u.aes; struct ccp_dm_workarea key, ctx, final_wa, tag; struct ccp_data src, dst; struct ccp_data aad; struct ccp_op op; unsigned int dm_offset; unsigned int authsize; unsigned int jobid; unsigned int ilen; bool in_place = true; /* Default value */ __be64 *final; int ret;
struct scatterlist *p_inp, sg_inp[2]; struct scatterlist *p_tag, sg_tag[2]; struct scatterlist *p_outp, sg_outp[2]; struct scatterlist *p_aad;
if (!aes->iv) return -EINVAL; . . . . The structure aad,src,dst… is defined in CODE-1 //CODE-2 …
op.init = 1; if (aes->aad_len > 0) { /* Step 1: Run a GHASH over the Additional Authenticated Data */ ret = ccp_init_data(&aad, cmd_q, p_aad, aes->aad_len, AES_BLOCK_SIZE, DMA_TO_DEVICE); // init `aad` if (ret) goto e_ctx;
op.u.aes.mode = CCP\_AES\_MODE\_GHASH;
op.u.aes.action = CCP\_AES\_GHASHAAD;
while (aad.sg\_wa.bytes\_left) {
ccp\_prepare\_data(&aad, NULL, &op, AES\_BLOCK\_SIZE, true);
ret = cmd\_q->ccp->vdata->perform->aes(&op);
if (ret) {
cmd->engine\_error = cmd\_q->cmd\_error;
goto e\_aad;
}
ccp\_process\_data(&aad, NULL, &op);
op.init = 0;
}
} // CODE-3 op.u.aes.mode = CCP_AES_MODE_GCTR; op.u.aes.action = aes->action;
if (ilen > 0) { /* Step 2: Run a GCTR over the plaintext */ in_place = (sg_virt(p_inp) == sg_virt(p_outp)) ? true : false;
ret = ccp\_init\_data(&src, cmd\_q, p\_inp, ilen,
AES\_BLOCK\_SIZE,
in\_place ? DMA\_BIDIRECTIONAL
: DMA\_TO\_DEVICE);
if (ret)
goto e\_ctx; // whill free the value and return.
if (in\_place) {
dst = src;
} else {
ret = ccp\_init\_data(&dst, cmd\_q, p\_outp, ilen,
AES\_BLOCK\_SIZE, DMA\_FROM\_DEVICE);
if (ret)
goto e\_src;
} . . . . . In CODE-2 `aad` will init which will be alloc a memory and then into CODE-3 if `src` init failed it will got `e_ctx`(following code show it) which not free `aad` until the function execute end. …
e_tag: ccp_dm_free(&final_wa);
e_dst: if (ilen > 0 && !in_place) ccp_free_data(&dst, cmd_q);
e_src: if (ilen > 0) ccp_free_data(&src, cmd_q);
e_aad: if (aes->aad_len) ccp_free_data(&aad, cmd_q);
e_ctx: ccp_dm_free(&ctx);
e_key: ccp_dm_free(&key);
return ret; }
And then this code is used to support AMD’s cryptographic co-processor.
The above is our analysis，I look forward to hearing from you soon
Have a nice day Best wishes
Peanuts Tencent Security XuanwuLab
From: Dan Carpenter <dan.carpenter () oracle com> Subject: [vs-plain] [PATCH RESEND] crypto: ccp - fix resource leaks in ccp_run_aes_gcm_cmd()
There are three bugs in this code:
- If we ccp_init_data() fails for &src then we need to free aad. Use goto e_aad instead of goto e_ctx.
- The label to free the &final_wa was named incorrectly as “e_tag” but it should have been "e_final_wa". One error path leaked &final_wa.
- The &tag was leaked on one error path. In that case, I added a free before the goto because the resource was local to that block.
Fixes: 36cf515b9bbe (“crypto: ccp - Enable support for AES GCM on v5 CCPs”) Reported-by: "minihanshen(沈明航)" <minihanshen () tencent com> Signed-off-by: Dan Carpenter <dan.carpenter () oracle com> Reviewed-by: John Allen <john.allen () amd com> Tested-by: John Allen <john.allen () amd com>
Resending because I screwed up the CC list and left off linux-distros. Sorry!
drivers/crypto/ccp/ccp-ops.c | 14 +++++++±----- 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c index bb88198c874e…aa4e1a500691 100644 — a/drivers/crypto/ccp/ccp-ops.c +++ b/drivers/crypto/ccp/ccp-ops.c @@ -778,7 +778,7 @@ ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd) in_place ? DMA_BIDIRECTIONAL : DMA_TO_DEVICE); if (ret)
goto e\_ctx;
goto e\_aad; if (in\_place) { dst = src;
@@ -863,7 +863,7 @@ ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd) op.u.aes.size = 0; ret = cmd_q->ccp->vdata->perform->aes(&op); if (ret)
goto e\_dst;
goto e\_final\_wa; if (aes->action == CCP\_AES\_ACTION\_ENCRYPT) { /\* Put the ciphered tag after the ciphertext. \*/
@@ -873,17 +873,19 @@ ccp_run_aes_gcm_cmd(struct ccp_cmd_queue *cmd_q, struct ccp_cmd *cmd) ret = ccp_init_dm_workarea(&tag, cmd_q, authsize, DMA_BIDIRECTIONAL); if (ret)
goto e\_tag;
goto e\_final\_wa; ret = ccp\_set\_dm\_area(&tag, 0, p\_tag, 0, authsize);
if (ret)goto e\_tag;
if (ret) {ccp\_dm\_free(&tag);goto e\_final\_wa;} ret = crypto\_memneq(tag.address, final\_wa.address, authsize) ? -EBADMSG : 0; ccp\_dm\_free(&tag); }
-e_tag: +e_final_wa: ccp_dm_free(&final_wa);
e_dst:
2.20.1
Current thread:
- Disclosure: CVE-2021-3744: crypto: ccp - fix resource leaks in ccp_run_aes_gcm_cmd() Marcus Meissner (Sep 14)