Messages in this thread | | | Subject | Re: [RFC][PATCH] almost certain bug in drivers/crypto/chelsio/chcr_algo.c:create_authenc_wr() | From | Ayush Sawal <> | Date | Fri, 21 Feb 2020 10:47:01 +0530 |
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On 2/15/2020 11:45 AM, Al Viro wrote:
> > kctx_len = (ntohl(KEY_CONTEXT_CTX_LEN_V(aeadctx->key_ctx_hdr)) > << 4) > - sizeof(chcr_req->key_ctx); > can't possibly be endian-safe. Look: ->key_ctx_hdr is __be32. And > KEY_CONTEXT_CTX_LEN_V is "shift up by 24 bits". On little-endian hosts it > sees > b0 b1 b2 b3 > in memory, inteprets that into b0 + (b1 << 8) + (b2 << 16) + (b3 << 24), > shifts up by 24, resulting in b0 << 24, does ntohl (byteswap on l-e), > gets b0 and shifts that up by 4. So we get b0 * 16 - sizeof(...). > > Sounds reasonable, but on b-e we get > b3 + (b2 << 8) + (b1 << 16) + (b0 << 24), shift up by 24, > yielding b3 << 24, do ntohl (no-op on b-e) and then shift up by 4. > Resulting in b3 << 28 - sizeof(...), i.e. slightly under b3 * 256M. > > Then we increase it some more and pass to alloc_skb() as size. > Somehow I doubt that we really want a quarter-gigabyte skb allocation > here... > > Note that when you are building those values in > #define FILL_KEY_CTX_HDR(ck_size, mk_size, d_ck, opad, ctx_len) \ > htonl(KEY_CONTEXT_VALID_V(1) | \ > KEY_CONTEXT_CK_SIZE_V((ck_size)) | \ > KEY_CONTEXT_MK_SIZE_V(mk_size) | \ > KEY_CONTEXT_DUAL_CK_V((d_ck)) | \ > KEY_CONTEXT_OPAD_PRESENT_V((opad)) | \ > KEY_CONTEXT_SALT_PRESENT_V(1) | \ > KEY_CONTEXT_CTX_LEN_V((ctx_len))) > ctx_len ends up in the first octet (i.e. b0 in the above), which > matches the current behaviour on l-e. If that's the intent, this > thing should've been > kctx_len = (KEY_CONTEXT_CTX_LEN_G(ntohl(aeadctx->key_ctx_hdr)) > << 4) > - sizeof(chcr_req->key_ctx); > instead - fetch after ntohl() we get (b0 << 24) + (b1 << 16) + (b2 << > 8) + b3, > shift it down by 24 (b0), resuling in b0 * 16 - sizeof(...) both on > l-e and > on b-e. > > PS: when sparse warns you about endianness problems, it might be worth > checking > if there really is something wrong. And I don't mean "slap __force > cast on it"... > > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk > <mailto:viro@zeniv.linux.org.uk>> > --- > diff -urN a/drivers/crypto/chelsio/chcr_algo.c > b/drivers/crypto/chelsio/chcr_algo.c > --- a/drivers/crypto/chelsio/chcr_algo.c > +++ b/drivers/crypto/chelsio/chcr_algo.c > @@ -2351,7 +2351,7 @@ static struct sk_buff *create_authenc_wr(struct > aead_request *req, > snents = sg_nents_xlen(req->src, req->assoclen + req->cryptlen, > CHCR_SRC_SG_SIZE, 0); > dst_size = get_space_for_phys_dsgl(dnents); > - kctx_len = (ntohl(KEY_CONTEXT_CTX_LEN_V(aeadctx->key_ctx_hdr)) > << 4) > + kctx_len = (KEY_CONTEXT_CTX_LEN_G(ntohl(aeadctx->key_ctx_hdr)) > << 4) > - sizeof(chcr_req->key_ctx); > transhdr_len = CIPHER_TRANSHDR_SIZE(kctx_len, dst_size); > reqctx->imm = (transhdr_len + req->assoclen + req->cryptlen) <
This was a genuine bug, thanks a lot for pointing it out and providing the fix.We are checking other sparse warns in our files, and soon we will fix the warnings.
Thanks, Ayush
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