Messages in this thread Patch in this message | | | From | Tycho Andersen <> | Subject | [PATCH 3/3] dh key: get rid of stack allocated array for zeroes | Date | Mon, 23 Apr 2018 19:03:21 -0600 |
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We're interested in getting rid of all of the stack allocated arrays in the kernel: https://lkml.org/lkml/2018/3/7/621
This case is interesting, since we really just need an array of bytes that are zero. The loop already ensures that if the array isn't exactly the right size that enough zero bytes will be copied in. So, instead of choosing this value to be the size of the hash, let's just choose it to be 256, since that is a common size, is not to big, and will not result in too many extra iterations of the loop.
v2: split out from other patch, just hardcode array size instead of dynamically allocating something the right size
Signed-off-by: Tycho Andersen <tycho@tycho.ws> CC: David Howells <dhowells@redhat.com> CC: James Morris <jmorris@namei.org> CC: "Serge E. Hallyn" <serge@hallyn.com> CC: Eric Biggers <ebiggers3@gmail.com> --- security/keys/dh.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/security/keys/dh.c b/security/keys/dh.c index 9fecaea6c298..74f8a853872e 100644 --- a/security/keys/dh.c +++ b/security/keys/dh.c @@ -162,8 +162,8 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen, goto err; if (zlen && h) { - u8 tmpbuffer[h]; - size_t chunk = min_t(size_t, zlen, h); + u8 tmpbuffer[256]; + size_t chunk = min_t(size_t, zlen, sizeof(tmpbuffer)); memset(tmpbuffer, 0, chunk); do { @@ -173,7 +173,7 @@ static int kdf_ctr(struct kdf_sdesc *sdesc, const u8 *src, unsigned int slen, goto err; zlen -= chunk; - chunk = min_t(size_t, zlen, h); + chunk = min_t(size_t, zlen, sizeof(tmpbuffer)); } while (zlen); } -- 2.17.0
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