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  1. 12 Mar, 2020 2 commits
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    • Al Viro's avatar
      crypto: chelsio - Endianess bug in create_authenc_wr · ff462ddf
      Al Viro authored 
      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: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      ff462ddf
    • Gustavo A. R. Silva's avatar
      crypto: s5p-sss - Replace zero-length array with flexible-array member · a4a70fa9
      Gustavo A. R. Silva authored 
      The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: default avatarGustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: default avatarKamil Konieczny <k.konieczny@samsung.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
      a4a70fa9
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