On Mon, Aug 07, 2023 at 02:04:05PM +0200, Arnd Bergmann wrote: > > See https://pastebin.com/raw/ip3tfpJF for a config that triggers this > on x86 with the chelsio and atmel drivers. The bcm driver is only > available on arm64, so you won't hit that one here. I also > see this with allmodconfig, as well as defconfig after enabling > CONFIG_FORTIFY_SOURCE and the three crypto drivers. OK I can reproduce this now: In file included from ../include/linux/string.h:254, from ../arch/x86/include/asm/page_32.h:18, from ../arch/x86/include/asm/page.h:14, from ../arch/x86/include/asm/processor.h:20, from ../arch/x86/include/asm/timex.h:5, from ../include/linux/timex.h:67, from ../include/linux/time32.h:13, from ../include/linux/time.h:60, from ../include/linux/stat.h:19, from ../include/linux/module.h:13, from ../drivers/crypto/atmel-sha.c:15: ../drivers/crypto/atmel-sha.c: In function ‘atmel_sha_hmac_compute_ipad_hash’: ../include/linux/fortify-string.h:57:33: error: ‘__builtin_memcpy’ accessing 129 or more bytes at offsets 304 and 176 overlaps 1 or more bytes at offset 304 [-Werror=restrict] 57 | #define __underlying_memcpy __builtin_memcpy | ^ ../include/linux/fortify-string.h:648:9: note: in expansion of macro ‘__underlying_memcpy’ 648 | __underlying_##op(p, q, __fortify_size); \ | ^~~~~~~~~~~~~ ../include/linux/fortify-string.h:693:26: note: in expansion of macro ‘__fortify_memcpy_chk’ 693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ | ^~~~~~~~~~~~~~~~~~~~ ../drivers/crypto/atmel-sha.c:1773:9: note: in expansion of macro ‘memcpy’ 1773 | memcpy(hmac->opad, hmac->ipad, bs); | ^~~~~~ ../include/linux/fortify-string.h:57:33: error: ‘__builtin_memcpy’ accessing 129 or more bytes at offsets 304 and 176 overlaps 1 or more bytes at offset 304 [-Werror=restrict] 57 | #define __underlying_memcpy __builtin_memcpy | ^ ../include/linux/fortify-string.h:648:9: note: in expansion of macro ‘__underlying_memcpy’ 648 | __underlying_##op(p, q, __fortify_size); \ | ^~~~~~~~~~~~~ ../include/linux/fortify-string.h:693:26: note: in expansion of macro ‘__fortify_memcpy_chk’ 693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, \ | ^~~~~~~~~~~~~~~~~~~~ ../drivers/crypto/atmel-sha.c:1773:9: note: in expansion of macro ‘memcpy’ 1773 | memcpy(hmac->opad, hmac->ipad, bs); | ^~~~~~ cc1: all warnings being treated as errors But why are we turning these warnings on if they're giving completely bogus false positives like this? struct atmel_sha_hmac_ctx { struct atmel_sha_ctx base; struct atmel_sha_hmac_key hkey; u32 ipad[SHA512_BLOCK_SIZE / sizeof(u32)]; u32 opad[SHA512_BLOCK_SIZE / sizeof(u32)]; atmel_sha_fn_t resume; }; struct atmel_sha_hmac_ctx *hmac = crypto_ahash_ctx(tfm); size_t bs = ctx->block_size; memcpy(hmac->opad, hmac->ipad, bs); The block_size is set by the algorithm, you can easily grep for it in atmel-sha.c and the biggest one there is SHA512_BLOCK_SIZE, which is how big hmac->ipad/hmac->opad are. So logically this code is perfectly fine. There is no way for the compiler to know how big ctx->block_size is. So why do we expect it to make deductions on how big bs can be? This warning looks broken to me. It looks like there is already a solution to this though. Just use unsafe_memcpy and be done with it. Cheers, -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
