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| author | Eric Biggers <ebiggers@google.com> | 2018-06-26 16:59:46 +0100 |
|---|---|---|
| committer | James Morris <james.morris@microsoft.com> | 2018-06-26 09:43:05 -0700 |
| commit | 3619dec5103dd999a777e3e4ea08c8f40a6ddc57 (patch) | |
| tree | baf202f770e183d2222468917a1e975d65bb9156 /security/keys | |
| parent | 2e20ce4a66b798671c60198ea2547d5e090dd991 (diff) | |
| download | linux-3619dec5103dd999a777e3e4ea08c8f40a6ddc57.tar.gz linux-3619dec5103dd999a777e3e4ea08c8f40a6ddc57.tar.bz2 linux-3619dec5103dd999a777e3e4ea08c8f40a6ddc57.zip | |
dh key: fix rounding up KDF output length
Commit 383203eff718 ("dh key: get rid of stack allocated array") changed
kdf_ctr() to assume that the length of key material to derive is a
multiple of the digest size. The length was supposed to be rounded up
accordingly. However, the round_up() macro was used which only gives
the correct result on power-of-2 arguments, whereas not all hash
algorithms have power-of-2 digest sizes. In some cases this resulted in
a write past the end of the 'outbuf' buffer.
Fix it by switching to roundup(), which works for non-power-of-2 inputs.
Reported-by: syzbot+486f97f892efeb2075a3@syzkaller.appspotmail.com
Reported-by: syzbot+29d17b7898b41ee120a5@syzkaller.appspotmail.com
Reported-by: syzbot+8a608baf8751184ec727@syzkaller.appspotmail.com
Reported-by: syzbot+d04e58bd384f1fe0b112@syzkaller.appspotmail.com
Fixes: 383203eff718 ("dh key: get rid of stack allocated array")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Tycho Andersen <tycho@tycho.ws>
Signed-off-by: James Morris <james.morris@microsoft.com>
Diffstat (limited to 'security/keys')
| -rw-r--r-- | security/keys/dh.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/security/keys/dh.c b/security/keys/dh.c index f7403821db7f..b203f7758f97 100644 --- a/security/keys/dh.c +++ b/security/keys/dh.c @@ -142,6 +142,8 @@ static void kdf_dealloc(struct kdf_sdesc *sdesc) * The src pointer is defined as Z || other info where Z is the shared secret * from DH and other info is an arbitrary string (see SP800-56A section * 5.8.1.2). + * + * 'dlen' must be a multiple of the digest size. */ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen, u8 *dst, unsigned int dlen, unsigned int zlen) @@ -205,8 +207,8 @@ static int keyctl_dh_compute_kdf(struct kdf_sdesc *sdesc, { uint8_t *outbuf = NULL; int ret; - size_t outbuf_len = round_up(buflen, - crypto_shash_digestsize(sdesc->shash.tfm)); + size_t outbuf_len = roundup(buflen, + crypto_shash_digestsize(sdesc->shash.tfm)); outbuf = kmalloc(outbuf_len, GFP_KERNEL); if (!outbuf) { |