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Date: Tue, 14 Sep 2021 17:29:11 +0200
From: Marcus Meissner <meissner@...e.de>
To: OSS Security List <oss-security@...ts.openwall.com>
Subject: Disclosure: CVE-2021-3744: crypto: ccp - fix resource leaks in
ccp_run_aes_gcm_cmd()
Hi,
CVE-2021-3744: crypto: ccp - fix resource leaks in ccp_run_aes_gcm_cmd()
This was reported by Tencent researcher <minihanshen@...cent.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@...cle.com>
Subject: [vs-plain] [PATCH RESEND] crypto: ccp - fix resource leaks in ccp_run_aes_gcm_cmd()
There are three bugs in this code:
1) If we ccp_init_data() fails for &src then we need to free aad.
Use goto e_aad instead of goto e_ctx.
2) 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.
3) 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@...cent.com>
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Reviewed-by: John Allen <john.allen@....com>
Tested-by: John Allen <john.allen@....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
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