Hi, I'm chasing a memory corruption with 4.8-rc7 as I'm observing random Oopses on ppc BE/LE systems (lpars, KVM guests). About 30% of issues is that module list gets corrupted, and "cat /proc/modules" or "lsmod" triggers an Oops, for example: [ 88.486041] Unable to handle kernel paging request for data at address 0x00000020 ... [ 88.487658] NIP [c00000000020f820] m_show+0xa0/0x240 [ 88.487689] LR [c00000000020f834] m_show+0xb4/0x240 [ 88.487719] Call Trace: [ 88.487736] [c0000004b605bbb0] [c00000000020f834] m_show+0xb4/0x240 (unreliable) [ 88.487796] [c0000004b605bc50] [c00000000045e73c] seq_read+0x36c/0x520 [ 88.487843] [c0000004b605bcf0] [c0000000004e1014] proc_reg_read+0x84/0x120 [ 88.487889] [c0000004b605bd30] [c00000000040df88] vfs_read+0xf8/0x380 [ 88.487934] [c0000004b605bde0] [c00000000040fd40] SyS_read+0x60/0x110 [ 88.487981] [c0000004b605be30] [c000000000009590] system_call+0x38/0xec 0x20 offset is module_use->source, module_use is NULL because module.source_list gets corrupted. The source of corruption appears to originate from a 'ahash' test for p8_ghash: cryptomgr_test alg_test alg_test_hash test_hash __test_hash ahash_partial_update shash_async_export memcpy With some extra traces [1], I'm seeing that ahash_partial_update() allocates 56 bytes for 'state', and then crypto_ahash_export() writes 76 bytes into it: [ 5.970887] __test_hash alg name p8_ghash, result: c000000004333ac0, key: c0000004b860a500, req: c0000004b860a380 [ 5.970963] state: c000000004333f00, statesize: 56 [ 5.970995] shash_default_export memcpy c000000004333f00 c0000004b860a3e0, len: 76 This seems to directly correspond with: p8_ghash_alg.descsize = sizeof(struct p8_ghash_desc_ctx) == 56 shash_tfm->descsize = sizeof(struct p8_ghash_desc_ctx) + crypto_shash_descsize(fallback) == 56 + 20 where 20 is presumably coming from "ghash_alg.descsize". My gut feeling was that these 2 should match, but I'd love to hear what crypto people think. Thank you, Jan [1] diff --git a/crypto/shash.c b/crypto/shash.c index a051541..49fe182 100644 --- a/crypto/shash.c +++ b/crypto/shash.c @@ -188,6 +188,8 @@ EXPORT_SYMBOL_GPL(crypto_shash_digest); static int shash_default_export(struct shash_desc *desc, void *out) { + int len = crypto_shash_descsize(desc->tfm); + printk("shash_default_export memcpy %p %p, len: %d\n", out, shash_desc_ctx(desc), len); memcpy(out, shash_desc_ctx(desc), crypto_shash_descsize(desc->tfm)); return 0; } diff --git a/crypto/testmgr.c b/crypto/testmgr.c index 5c9d5a5..2e54579 100644 --- a/crypto/testmgr.c +++ b/crypto/testmgr.c @@ -218,6 +218,8 @@ static int ahash_partial_update(struct ahash_request **preq, pr_err("alt: hash: Failed to alloc state for %s\n", algo); goto out_nostate; } + printk("state: %p, statesize: %d\n", state, statesize); + ret = crypto_ahash_export(req, state); if (ret) { pr_err("alt: hash: Failed to export() for %s\n", algo); @@ -288,6 +290,7 @@ static int __test_hash(struct crypto_ahash *tfm, struct hash_testvec *template, "%s\n", algo); goto out_noreq; } + printk("__test_hash alg name %s, result: %p, key: %p, req: %p\n", algo, result, key, req); ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG, tcrypt_complete, &tresult); -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html