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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: 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 () 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
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- Disclosure: CVE-2021-3744: crypto: ccp - fix resource leaks in ccp_run_aes_gcm_cmd() Marcus Meissner (Sep 14)