Re: linux-next: manual merge of the modules tree with the tree
From: Kees Cook <hidden>
Date: 2012-10-22 02:09:36
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On Sun, Oct 21, 2012 at 6:35 PM, Stephen Rothwell [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Hi Rusty, Today's linux-next merge of the modules tree got a conflict in kernel/module.c between commit caabe240574a ("MODSIGN: Move the magic string to the end of a module and eliminate the search") from Linus' tree and commit 0250abdeec54 ("module: add syscall to load module from fd") from the modules tree. I fixed it up (I think - see below) and can carry the fix as necessary (no action is required). I do wonder why the above change in Linus' tree seems to have bypassed the modules maintainer. -- Cheers, Stephen Rothwell sfr@canb.auug.org.au diff --cc kernel/module.c index 6085f5e,261bf82..0000000--- a/kernel/module.c +++ b/kernel/module.c@@@ -2420,18 -2422,27 +2422,18 @@@ static inline void kmemleak_load_module #endif #ifdef CONFIG_MODULE_SIG - static int module_sig_check(struct load_info *info, - const void *mod, unsigned long *_len) + static int module_sig_check(struct load_info *info) { int err = -ENOKEY; - unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; - unsigned long len = *_len; + const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1; + const void *mod = info->hdr;
I got rid of "mod" when I did my merge of these changes against Linus's tree, but I had to cast it in the memcmp, so probably best to just keep "mod".
- const void *p = mod, *end = mod + info->len;
++ unsigned long len = info->len;
- /* Poor man's memmem. */
- while ((p = memchr(p, MODULE_SIG_STRING[0], end - p))) {
- if (p + markerlen > end)
- break;
-
- if (memcmp(p, MODULE_SIG_STRING, markerlen) == 0) {
- const void *sig = p + markerlen;
- /* Truncate module up to signature. */
- info->len = p - mod;
- err = mod_verify_sig(mod, info->len,
- sig, end - sig);
- break;
- }
- p++;
+ if (len > markerlen &&
+ memcmp(mod + len - markerlen, MODULE_SIG_STRING, markerlen) == 0) {
+ /* We truncate the module to discard the signature */
- *_len -= markerlen;
- err = mod_verify_sig(mod, _len);
++ info->len -= markerlen;
++ err = mod_verify_sig(mod, &info->len);
}
if (!err) {-Kees -- Kees Cook Chrome OS Security