GIT: unionfs2-2.6.27.y: kbuild: Fix modpost segfault

[Erez Zadok]

commit 4baaa88700f665504702646b908fd7240425bdb5
Author: Krzysztof Halasa <khc at pm.waw.pl>
Date:   Fri Jun 11 01:08:20 2010 +0200

    kbuild: Fix modpost segfault
    
    commit 1c938663d58b5b2965976a6f54cc51b5d6f691aa upstream.
    
    Alan <alan at clueserver.org> writes:
    
    > program: /home/alan/GitTrees/linux-2.6-mid-ref/scripts/mod/modpost -o
    > Module.symvers -S vmlinux.o
    >
    > Program received signal SIGSEGV, Segmentation fault.
    
    It just hit me.
    It's the offset calculation in reloc_location() which overflows:
            return (void *)elf->hdr + sechdrs[section].sh_offset +
                   (r->r_offset - sechdrs[section].sh_addr);
    
    E.g. for the first rodata r entry:
    r->r_offset < sechdrs[section].sh_addr
    and the expression in the parenthesis produces 0xFFFFFFE0 or something
    equally wise.
    
    Reported-by: Alan <alan at clueserver.org>
    Signed-off-by: Krzysztof Hałasa <khc at pm.waw.pl>
    Tested-by: Alan <alan at clueserver.org>
    Signed-off-by: Michal Marek <mmarek at suse.cz>
    Signed-off-by: Greg Kroah-Hartman <gregkh at suse.de>

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index f05e36a..78480c2 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1292,7 +1292,7 @@ static unsigned int *reloc_location(struct elf_info *elf,
 	int section = sechdr->sh_info;
 
 	return (void *)elf->hdr + sechdrs[section].sh_offset +
-		(r->r_offset - sechdrs[section].sh_addr);
+		r->r_offset - sechdrs[section].sh_addr;
 }
 
 static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r)