Re: Linux 2.6.34-rc3 + CAN build problem

[Eric Dumazet <eric.dumazet@gmail.com>]

Le samedi 10 avril 2010 à 10:13 +0200, Németh Márton a écrit :
> Hi,
> 
> I have some problem building Liunux kernel 2.6.34-rc3 with the attached .config:
> 
> $ make clean bzImage modules
> [...]
>   CC      net/socket.o
>   LD      net/802/built-in.o
>   LD      net/can/built-in.o
>   CC [M]  net/can/bcm.o
>   CC [M]  net/can/raw.o
> In file included from /mnt/store/nmarci/src/linux-2.6.34-rc3/arch/x86/include/asm/uaccess.h:571,
>                  from include/net/checksum.h:25,
>                  from include/linux/skbuff.h:28,
>                  from include/linux/if_ether.h:124,
>                  from include/linux/netdevice.h:29,
>                  from net/can/raw.c:48:
> In function ‘copy_from_user’,
>     inlined from ‘raw_setsockopt’ at net/can/raw.c:447:
> /mnt/store/nmarci/src/linux-2.6.34-rc3/arch/x86/include/asm/uaccess_32.h:212: error: call to ‘copy_from_user_overflow’ declared with attribute error:
> copy_from_user() buffer size is not provably correct
> make[2]: *** [net/can/raw.o] Error 1
> make[1]: *** [net/can] Error 2
> make: *** [net] Error 2
> 
> 

Could you give us your compiler version ?

Code is fine, but compiler a bit dumb :(

[PATCH] can: avoids a false warning

At this point optlen == sizeof(sfilter) but some compilers are dumb.

Reported-by: Németh Márton <nm127@freemail.h
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
---
diff --git a/net/can/raw.c b/net/can/raw.c
index 3a7dffb..da99cf1 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -445,7 +445,7 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
 				return -EFAULT;
 			}
 		} else if (count == 1) {
-			if (copy_from_user(&sfilter, optval, optlen))
+			if (copy_from_user(&sfilter, optval, sizeof(sfilter)))
 				return -EFAULT;
 		}