From cb4f43bf87eb7332b3df1e78e50dee2dffea06f8 Mon Sep 17 00:00:00 2001 From: Hauke Mehrtens Date: Mon, 12 Feb 2018 23:59:51 +0100 Subject: [PATCH] uapi/if_ether.h: move __UAPI_DEF_ETHHDR libc define commit da360299b6734135a5f66d7db458dcc7801c826a upstream. This fixes a compile problem of some user space applications by not including linux/libc-compat.h in uapi/if_ether.h. linux/libc-compat.h checks which "features" the header files, included from the libc, provide to make the Linux kernel uapi header files only provide no conflicting structures and enums. If a user application mixes kernel headers and libc headers it could happen that linux/libc-compat.h gets included too early where not all other libc headers are included yet. Then the linux/libc-compat.h would not prevent all the redefinitions and we run into compile problems. This patch removes the include of linux/libc-compat.h from uapi/if_ether.h to fix the recently introduced case, but not all as this is more or less impossible. It is no problem to do the check directly in the if_ether.h file and not in libc-compat.h as this does not need any fancy glibc header detection as glibc never provided struct ethhdr and should define __UAPI_DEF_ETHHDR by them self when they will provide this. The following test program did not compile correctly any more: #include #include #include int main(void) { return 0; } Fixes: 6926e041a892 ("uapi/if_ether.h: prevent redefinition of struct ethhdr") Reported-by: Guillaume Nault Cc: # 4.15 Signed-off-by: Hauke Mehrtens Signed-off-by: David S. Miller Cc: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman --- include/uapi/linux/if_ether.h | 6 +++++- include/uapi/linux/libc-compat.h | 6 ------ 2 files changed, 5 insertions(+), 7 deletions(-) diff --git a/include/uapi/linux/if_ether.h b/include/uapi/linux/if_ether.h index cb490cd9376f..373afec2ed34 100644 --- a/include/uapi/linux/if_ether.h +++ b/include/uapi/linux/if_ether.h @@ -22,7 +22,6 @@ #define _UAPI_LINUX_IF_ETHER_H #include -#include /* * IEEE 802.3 Ethernet magic constants. The frame sizes omit the preamble @@ -137,6 +136,11 @@ * This is an Ethernet frame header. */ +/* allow libcs like musl to deactivate this, glibc does not implement this. */ +#ifndef __UAPI_DEF_ETHHDR +#define __UAPI_DEF_ETHHDR 1 +#endif + #if __UAPI_DEF_ETHHDR struct ethhdr { unsigned char h_dest[ETH_ALEN]; /* destination eth addr */ diff --git a/include/uapi/linux/libc-compat.h b/include/uapi/linux/libc-compat.h index 5da44c571cdd..e4f048ee7043 100644 --- a/include/uapi/linux/libc-compat.h +++ b/include/uapi/linux/libc-compat.h @@ -184,10 +184,4 @@ #endif /* __GLIBC__ */ -/* Definitions for if_ether.h */ -/* allow libcs like musl to deactivate this, glibc does not implement this. */ -#ifndef __UAPI_DEF_ETHHDR -#define __UAPI_DEF_ETHHDR 1 -#endif - #endif /* _UAPI_LIBC_COMPAT_H */