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Message-ID: <1329818517.3639.29.camel@mfleming-mobl1.ger.corp.intel.com> Date: Tue, 21 Feb 2012 10:01:57 +0000 From: Matt Fleming <matt.fleming@...el.com> To: Stephen Rothwell <sfr@...b.auug.org.au> Cc: "H. Peter Anvin" <hpa@...ux.intel.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: build failure in Linus' tree with gcc 4.4.3 On Mon, 2012-02-20 at 09:43 +0000, Matt Fleming wrote: > On Mon, 2012-02-20 at 14:22 +1100, Stephen Rothwell wrote: > > Which is all endian specific code that will run on the host when building > > the kernel ... > > Gah, right. I didn't think about cross-building this code. > > Thanks Stephen, I'll fix this up. Looks like the segfault is caused by an unaligned access? How does this patch look? >From 54b2707a6a911330d8db2f4ec2fb1baa5e38acf9 Mon Sep 17 00:00:00 2001 From: Matt Fleming <matt.fleming@...el.com> Date: Mon, 20 Feb 2012 17:32:42 +0000 Subject: [PATCH] x86, efi: Fix segfault caused by unaligned access We need to use memcpy() instead of directly dereferencing a pointer because memcpy() correctly handles the case where the source/destination are unaligned, which can lead to a segfault when cross-building an x86 kernel on risc architectures. Stephen Rothwell noticed this bug when he hit a segfault while cross-building an x86_64 allmodconfig kernel on PowerPC. Cc: H. Peter Anvin <hpa@...or.com> Reported-by: Stephen Rothwell <sfr@...b.auug.org.au> Signed-off-by: Matt Fleming <matt.fleming@...el.com> --- arch/x86/boot/tools/build.c | 26 ++++++++++++++------------ 1 files changed, 14 insertions(+), 12 deletions(-) diff --git a/arch/x86/boot/tools/build.c b/arch/x86/boot/tools/build.c index 4e9bd6b..b4d85b5 100644 --- a/arch/x86/boot/tools/build.c +++ b/arch/x86/boot/tools/build.c @@ -200,36 +200,38 @@ int main(int argc, char ** argv) #ifdef CONFIG_EFI_STUB file_sz = sz + i + ((sys_size * 16) - sz); - pe_header = *(unsigned int *)&buf[0x3c]; + memcpy(&pe_header, &buf[0x3c], sizeof(pe_header)); /* Size of code */ - *(unsigned int *)&buf[pe_header + 0x1c] = file_sz; + memcpy(&buf[pe_header + 0x1c], &file_sz, sizeof(file_sz)); /* Size of image */ - *(unsigned int *)&buf[pe_header + 0x50] = file_sz; + memcpy(&buf[pe_header + 0x50], &file_sz, sizeof(file_sz)); #ifdef CONFIG_X86_32 /* Address of entry point */ - *(unsigned int *)&buf[pe_header + 0x28] = i; + memcpy(&buf[pe_header + 0x28], &i, sizeof(i)); /* .text size */ - *(unsigned int *)&buf[pe_header + 0xb0] = file_sz; + memcpy(&buf[pe_header + 0xb0], &file_sz, sizeof(file_sz)); /* .text size of initialised data */ - *(unsigned int *)&buf[pe_header + 0xb8] = file_sz; + memcpy(&buf[pe_header + 0xb8], &file_sz, sizeof(file_sz)); #else + /* .text size */ + memcpy(&buf[pe_header + 0xc0], &file_sz, sizeof(file_sz)); + + /* .text size of initialised data */ + memcpy(&buf[pe_header + 0xc8], &file_sz, sizeof(file_sz)); + /* * Address of entry point. startup_32 is at the beginning and * the 64-bit entry point (startup_64) is always 512 bytes * after. */ - *(unsigned int *)&buf[pe_header + 0x28] = i + 512; + file_sz = i + 512; + memcpy(&buf[pe_header + 0x28], &file_sz, sizeof(file_sz)); - /* .text size */ - *(unsigned int *)&buf[pe_header + 0xc0] = file_sz; - - /* .text size of initialised data */ - *(unsigned int *)&buf[pe_header + 0xc8] = file_sz; #endif /* CONFIG_X86_32 */ #endif /* CONFIG_EFI_STUB */ -- 1.7.4.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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