tags 456205 patch thanks Hi Ghe,
I can confirm Bob's report that this code is an issue on alpha. The CMSG_SPACE() macro unfortunately only ensures that the buffer is large enough to /permit/ an aligned read without reading past the end of the buffer; it does not ensure that the buffer itself is aligned, or allocate enough space to permit an aligned read offset into the buffer if the buffer isn't aligned. So the fix Bob proposes is somewhat over-reaching, in that it will force 8-byte alignment even on archs that don't require it and waste a few bytes on the stack in the process; but I don't think that should be a blocker for implementing this patch, considering this bug almost certainly causes radvd to die with SIGBUS on sparc - I haven't tested this myself, or else I would raise the bug's severity to 'serious'. Attached is a debdiff that implements Bob's fix. Let me know if you would like me to upload an NMU for this. Cheers, -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ [EMAIL PROTECTED] [EMAIL PROTECTED]
diff -u radvd-1.1/debian/changelog radvd-1.1/debian/changelog --- radvd-1.1/debian/changelog +++ radvd-1.1/debian/changelog @@ -1,3 +1,13 @@ +radvd (1:1.1-2.1) UNRELEASED; urgency=low + + * Non-maintainer upload for the alpha port. + * Fix the alignment of the "chdr" buffer in send.c, so that we stop getting + unaligned traps that make the process run much less efficiently. This + probably also causes radvd to crash outright on sparc, though this has + not been confirmed. Thanks to Bob Tracy for the patch. Closes: #456205. + + -- Steve Langasek <[EMAIL PROTECTED]> Thu, 28 Aug 2008 01:19:30 -0700 + radvd (1:1.1-2) unstable; urgency=low * Migrated to unstable only in patch2: unchanged: --- radvd-1.1.orig/debian/patches/send.c-unaligned-traps.patch +++ radvd-1.1/debian/patches/send.c-unaligned-traps.patch @@ -0,0 +1,11 @@ +--- radvd-1.1.orig/send.c ++++ radvd-1.1/send.c +@@ -27,7 +27,7 @@ + struct msghdr mhdr; + struct cmsghdr *cmsg; + struct iovec iov; +- char chdr[CMSG_SPACE(sizeof(struct in6_pktinfo))]; ++ char __attribute__((aligned(8))) chdr[CMSG_SPACE(sizeof(struct in6_pktinfo))]; + struct nd_router_advert *radvert; + struct AdvPrefix *prefix; + struct AdvRoute *route;
