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:
int main(void) { return 0; }
Fixes: 6926e041a892 ("uapi/if_ether.h: prevent redefinition of struct ethhdr") Reported-by: Guillaume Nault g.nault@alphalink.fr Cc: stable@vger.kernel.org # 4.15 Signed-off-by: Hauke Mehrtens hauke@hauke-m.de --- 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 f8cb5760ea4f..8bbbcb5cd94b 100644 --- a/include/uapi/linux/if_ether.h +++ b/include/uapi/linux/if_ether.h @@ -23,7 +23,6 @@ #define _UAPI_LINUX_IF_ETHER_H
#include <linux/types.h> -#include <linux/libc-compat.h>
/* * IEEE 802.3 Ethernet magic constants. The frame sizes omit the preamble @@ -151,6 +150,11 @@ * 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 fc29efaa918c..8254c937c9f4 100644 --- a/include/uapi/linux/libc-compat.h +++ b/include/uapi/linux/libc-compat.h @@ -264,10 +264,4 @@
#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 */
On 02/12/2018 11:59 PM, Hauke Mehrtens wrote:
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:
int main(void) { return 0; }
git removed the included here:
#include <linux/if_ether.h> #include <netinet/in.h> #include <linux/in.h>
int main(void) { return 0; }
From: Hauke Mehrtens hauke@hauke-m.de Date: Tue, 13 Feb 2018 00:01:26 +0100
On 02/12/2018 11:59 PM, Hauke Mehrtens wrote:
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:
int main(void) { return 0; }
git removed the included here:
#include <linux/if_ether.h> #include <netinet/in.h> #include <linux/in.h>
int main(void) { return 0; }
Applied with this fixed up, thanks!
On Tue, Feb 13, 2018 at 11:24:07AM -0500, David Miller wrote:
From: Hauke Mehrtens hauke@hauke-m.de Date: Tue, 13 Feb 2018 00:01:26 +0100
On 02/12/2018 11:59 PM, Hauke Mehrtens wrote:
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:
int main(void) { return 0; }
git removed the included here:
#include <linux/if_ether.h> #include <netinet/in.h> #include <linux/in.h>
int main(void) { return 0; }
Applied with this fixed up, thanks!
Works fine. Thanks Hauke!
linux-stable-mirror@lists.linaro.org
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David Miller -
Guillaume Nault -
Hauke Mehrtens