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kbuild: Fix modpost segfault

PATCH In review Michal Marek 3 participants 5 messages Jun 29, 2010

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Michal Marek

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#0 lore raw

PATCH 1/1 kbuild: Fix modpost segfault

Hi Greg,

please add this to stable, it's a bug that started showing up with newer gcc. The upstream commit is 1c938663d58b5b2965976a6f54cc51b5d6f691aa.

Thanks,
Michal

From: Krzysztof Halasa <[email protected]>

Quoted 4 lines · Alan

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 <[email protected]>
Signed-off-by Krzysztof Hałasa <[email protected]>
Tested-by Alan <[email protected]>
Signed-off-by Michal Marek <[email protected]>
scripts/mod/modpost.c +1 -1
index 3318692..f877900 100644
@@ -1342,7 +1342,7 @@ 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)
#1 lore raw
Quoted 4 lines · Michal Marek

Hi Greg,

please add this to stable, it's a bug that started showing up with newer gcc. The upstream commit is 1c938663d58b5b2965976a6f54cc51b5d6f691aa.

What -stable kernels do you want it applied to? .27, .32, .33, and/or .34?

thanks,

greg k-h

author
#2 lore raw
Quoted 8 lines · Greg KH
Quoted 4 lines · Michal Marek

Hi Greg,

please add this to stable, it's a bug that started showing up with newer gcc. The upstream commit is 1c938663d58b5b2965976a6f54cc51b5d6f691aa.

What -stable kernels do you want it applied to? .27, .32, .33, and/or .34?

I'd say all of them. I just tried it and applies cleanly.

Michal

#3 lore raw
Quoted 11 lines · Michal Marek
Quoted 8 lines · Greg KH
Quoted 4 lines · Michal Marek

Hi Greg,

please add this to stable, it's a bug that started showing up with newer gcc. The upstream commit is 1c938663d58b5b2965976a6f54cc51b5d6f691aa.

What -stable kernels do you want it applied to? .27, .32, .33, and/or .34?

I'd say all of them. I just tried it and applies cleanly.

Ok, thanks, will do.

greg k-h

#4 lore raw
Quoted 8 lines · Greg KH
Quoted 7 lines · Michal Marek
Quoted 6 lines · Greg KH
Quoted 4 lines · Michal Marek

Hi Greg,

please add this to stable, it's a bug that started showing up with newer gcc. The upstream commit is 1c938663d58b5b2965976a6f54cc51b5d6f691aa.

Quoted 6 lines
Quoted 4 lines
Quoted 2 lines

What -stable kernels do you want it applied to? .27, .32, .33, and/or .34?

I'd say all of them. I just tried it and applies cleanly.

Ok, thanks, will do.

Thanks. That fixes a major build problem for me.