laforge submitted this change.
osmo_io: Fix misalignment of iofd->cmsg used as struct cmsghdr
Fixes following ASAN runtime error:
"""
src/stream.c:398:47: runtime error: member access within misaligned address 0x516000012b81 for type 'struct cmsghdr', which requires 8 byte alignment
0x516000012b81: note: pointer points here
51 00 00 00 30 00 00 00 00 00 00 00 84 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 03
^
"""
Current GCC documentation [1] states that __attribute__ ((__aligned__
(alignment))) is the older sytnax. The newer _Alignas mimics the
standarized alignas() in C23. Since we build with CLAGS=-std=gnu11 we
are fine using _Alignas, which was introduced in C11.
[1] https://www.gnu.org/software/c-intro-and-ref/manual/html_node/Type-Alignment.html
Related: OS#6905
Change-Id: Ia80dfc4dbffe85514b18dcf8d36b85bfafd76d64
---
M src/core/osmo_io_internal.h
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/src/core/osmo_io_internal.h b/src/core/osmo_io_internal.h
index c15262b..4f35fee 100644
--- a/src/core/osmo_io_internal.h
+++ b/src/core/osmo_io_internal.h
@@ -170,8 +170,11 @@
/*! msghdr is in the cancel_queue list */
bool in_cancel_queue;
- /*! control message buffer for passing sctp_sndrcvinfo along */
- char cmsg[0]; /* size is determined by iofd->cmsg_size on recvmsg, and by mcghdr->msg_controllen on sendmsg */
+ /*! control message buffer for passing sctp_sndrcvinfo along.
+ * Size is determined by iofd->cmsg_size on recvmsg, and by mcghdr->msg_controllen on sendmsg.
+ * Alignment of the array is required due to cast to "struct cmsghdr", eg. by CMSG_FIRSTHDR().
+ */
+ char _Alignas(struct cmsghdr) cmsg[0];
};
enum iofd_seg_act {
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