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* [PATCH] Load bzImages smaller than 32 KiB
@ 2012-06-01 15:59 Eric Biggers
  2012-06-04 23:14 ` Simon Horman
  0 siblings, 1 reply; 4+ messages in thread
From: Eric Biggers @ 2012-06-01 15:59 UTC (permalink / raw)
  To: kexec

Allow bzImages smaller than 32KiB to be kexec'ed.

The current code will fail to load a bzImage smaller than 32768 bytes (sizeof
struct x86_linux_header), but the 'memdisk' program that comes with syslinux is
only about 26 KiB.  This patch changes the minimum size to 1024 bytes (2
sectors), which appears to be the limit that syslinux enforces.

Removed the "tail" field of struct x86_linux_header because it doesn't seem to
actually be used (is there a reason for it?).

Also, note that bzImage_probe() was incorrectly using `sizeof (header)', even
though header is a pointer.

diff --git a/include/x86/x86-linux.h b/include/x86/x86-linux.h
index 59d35c9..2ebcc3a 100644
--- a/include/x86/x86-linux.h
+++ b/include/x86/x86-linux.h
@@ -233,7 +233,6 @@ struct x86_linux_header {
 	uint32_t high_base;			/* 0x24C */
 	uint32_t high_memsz;			/* 0x250 */
 	uint32_t high_filesz;			/* 0x254 */
-	uint32_t tail[32*1024 - 0x258];		/* 0x258 */
 #else
 	uint32_t kernel_alignment;		/* 0x230 */
 	uint8_t  relocatable_kernel;		/* 0x234 */
@@ -241,7 +240,6 @@ struct x86_linux_header {
 	uint32_t cmdline_size;                  /* 0x238 */
 	uint32_t hardware_subarch;              /* 0x23C */
 	uint64_t hardware_subarch_data;         /* 0x240 */
-	uint8_t  tail[32*1024 - 0x248];		/* 0x248 */
 #endif
 } PACKED;
 
diff --git a/kexec/arch/i386/kexec-bzImage.c b/kexec/arch/i386/kexec-bzImage.c
index 54c4427..6998587 100644
--- a/kexec/arch/i386/kexec-bzImage.c
+++ b/kexec/arch/i386/kexec-bzImage.c
@@ -44,7 +44,10 @@ static const int probe_debug = 0;
 int bzImage_probe(const char *buf, off_t len)
 {
 	const struct x86_linux_header *header;
-	if ((uintmax_t)len < (uintmax_t)sizeof(header)) {
+	if ((uintmax_t)len < (uintmax_t)(2 * 512)) {
+		if (probe_debug) {
+			fprintf(stderr, "File is too short to be a bzImage!\n");
+		}
 		return -1;
 	}
 	header = (const struct x86_linux_header *)buf;
@@ -118,7 +121,7 @@ int do_bzImage_load(struct kexec_info *info,
 	/*
 	 * Find out about the file I am about to load.
 	 */
-	if ((uintmax_t)kernel_len < (uintmax_t)sizeof(setup_header)) {
+	if ((uintmax_t)kernel_len < (uintmax_t)(2 * 512)) {
 		return -1;
 	}
 	memcpy(&setup_header, kernel, sizeof(setup_header));

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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] Load bzImages smaller than 32 KiB
  2012-06-01 15:59 [PATCH] Load bzImages smaller than 32 KiB Eric Biggers
@ 2012-06-04 23:14 ` Simon Horman
  2012-06-05 23:46   ` Eric Biggers
  0 siblings, 1 reply; 4+ messages in thread
From: Simon Horman @ 2012-06-04 23:14 UTC (permalink / raw)
  To: Eric Biggers; +Cc: kexec

On Fri, Jun 01, 2012 at 10:59:32AM -0500, Eric Biggers wrote:
> Allow bzImages smaller than 32KiB to be kexec'ed.
> 
> The current code will fail to load a bzImage smaller than 32768 bytes (sizeof
> struct x86_linux_header), but the 'memdisk' program that comes with syslinux is
> only about 26 KiB.  This patch changes the minimum size to 1024 bytes (2
> sectors), which appears to be the limit that syslinux enforces.
> 
> Removed the "tail" field of struct x86_linux_header because it doesn't seem to
> actually be used (is there a reason for it?).
> 
> Also, note that bzImage_probe() was incorrectly using `sizeof (header)', even
> though header is a pointer.

Hi Eric,

could you please supply a signed-off-by line so I can apply this patch?

Thanks.

> 
> diff --git a/include/x86/x86-linux.h b/include/x86/x86-linux.h
> index 59d35c9..2ebcc3a 100644
> --- a/include/x86/x86-linux.h
> +++ b/include/x86/x86-linux.h
> @@ -233,7 +233,6 @@ struct x86_linux_header {
>  	uint32_t high_base;			/* 0x24C */
>  	uint32_t high_memsz;			/* 0x250 */
>  	uint32_t high_filesz;			/* 0x254 */
> -	uint32_t tail[32*1024 - 0x258];		/* 0x258 */
>  #else
>  	uint32_t kernel_alignment;		/* 0x230 */
>  	uint8_t  relocatable_kernel;		/* 0x234 */
> @@ -241,7 +240,6 @@ struct x86_linux_header {
>  	uint32_t cmdline_size;                  /* 0x238 */
>  	uint32_t hardware_subarch;              /* 0x23C */
>  	uint64_t hardware_subarch_data;         /* 0x240 */
> -	uint8_t  tail[32*1024 - 0x248];		/* 0x248 */
>  #endif
>  } PACKED;
>  
> diff --git a/kexec/arch/i386/kexec-bzImage.c b/kexec/arch/i386/kexec-bzImage.c
> index 54c4427..6998587 100644
> --- a/kexec/arch/i386/kexec-bzImage.c
> +++ b/kexec/arch/i386/kexec-bzImage.c
> @@ -44,7 +44,10 @@ static const int probe_debug = 0;
>  int bzImage_probe(const char *buf, off_t len)
>  {
>  	const struct x86_linux_header *header;
> -	if ((uintmax_t)len < (uintmax_t)sizeof(header)) {
> +	if ((uintmax_t)len < (uintmax_t)(2 * 512)) {
> +		if (probe_debug) {
> +			fprintf(stderr, "File is too short to be a bzImage!\n");
> +		}
>  		return -1;
>  	}
>  	header = (const struct x86_linux_header *)buf;
> @@ -118,7 +121,7 @@ int do_bzImage_load(struct kexec_info *info,
>  	/*
>  	 * Find out about the file I am about to load.
>  	 */
> -	if ((uintmax_t)kernel_len < (uintmax_t)sizeof(setup_header)) {
> +	if ((uintmax_t)kernel_len < (uintmax_t)(2 * 512)) {
>  		return -1;
>  	}
>  	memcpy(&setup_header, kernel, sizeof(setup_header));
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

^ permalink raw reply	[flat|nested] 4+ messages in thread
* Re: [PATCH] Load bzImages smaller than 32 KiB
  2012-06-04 23:14 ` Simon Horman
@ 2012-06-05 23:46   ` Eric Biggers
  2012-06-13  1:33     ` Simon Horman
  0 siblings, 1 reply; 4+ messages in thread
From: Eric Biggers @ 2012-06-05 23:46 UTC (permalink / raw)
  To: Simon Horman; +Cc: kexec

Allow bzImages smaller than 32KiB to be kexec'ed.

The current code will fail to load a bzImage smaller than 32768 bytes (sizeof
struct x86_linux_header), but the 'memdisk' program that comes with syslinux is
only about 26 KiB.  This patch changes the minimum size to 1024 bytes (2
sectors), which appears to be the limit that syslinux enforces.

Removed the "tail" field of struct x86_linux_header because it doesn't seem to
actually be used (is there a reason for it?).

Also, note that bzImage_probe() was incorrectly using `sizeof (header)', even
though header is a pointer.

Signed-off-by: Eric Biggers <ebiggers3@gmail.com>

diff --git a/include/x86/x86-linux.h b/include/x86/x86-linux.h
index 59d35c9..2ebcc3a 100644
--- a/include/x86/x86-linux.h
+++ b/include/x86/x86-linux.h
@@ -233,7 +233,6 @@ struct x86_linux_header {
 	uint32_t high_base;			/* 0x24C */
 	uint32_t high_memsz;			/* 0x250 */
 	uint32_t high_filesz;			/* 0x254 */
-	uint32_t tail[32*1024 - 0x258];		/* 0x258 */
 #else
 	uint32_t kernel_alignment;		/* 0x230 */
 	uint8_t  relocatable_kernel;		/* 0x234 */
@@ -241,7 +240,6 @@ struct x86_linux_header {
 	uint32_t cmdline_size;                  /* 0x238 */
 	uint32_t hardware_subarch;              /* 0x23C */
 	uint64_t hardware_subarch_data;         /* 0x240 */
-	uint8_t  tail[32*1024 - 0x248];		/* 0x248 */
 #endif
 } PACKED;
 
diff --git a/kexec/arch/i386/kexec-bzImage.c b/kexec/arch/i386/kexec-bzImage.c
index 54c4427..6998587 100644
--- a/kexec/arch/i386/kexec-bzImage.c
+++ b/kexec/arch/i386/kexec-bzImage.c
@@ -44,7 +44,10 @@ static const int probe_debug = 0;
 int bzImage_probe(const char *buf, off_t len)
 {
 	const struct x86_linux_header *header;
-	if ((uintmax_t)len < (uintmax_t)sizeof(header)) {
+	if ((uintmax_t)len < (uintmax_t)(2 * 512)) {
+		if (probe_debug) {
+			fprintf(stderr, "File is too short to be a bzImage!\n");
+		}
 		return -1;
 	}
 	header = (const struct x86_linux_header *)buf;
@@ -118,7 +121,7 @@ int do_bzImage_load(struct kexec_info *info,
 	/*
 	 * Find out about the file I am about to load.
 	 */
-	if ((uintmax_t)kernel_len < (uintmax_t)sizeof(setup_header)) {
+	if ((uintmax_t)kernel_len < (uintmax_t)(2 * 512)) {
 		return -1;
 	}
 	memcpy(&setup_header, kernel, sizeof(setup_header));


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

^ permalink raw reply related	[flat|nested] 4+ messages in thread
* Re: [PATCH] Load bzImages smaller than 32 KiB
  2012-06-05 23:46   ` Eric Biggers
@ 2012-06-13  1:33     ` Simon Horman
  0 siblings, 0 replies; 4+ messages in thread
From: Simon Horman @ 2012-06-13  1:33 UTC (permalink / raw)
  To: Eric Biggers; +Cc: kexec

On Tue, Jun 05, 2012 at 07:46:07PM -0400, Eric Biggers wrote:
> Allow bzImages smaller than 32KiB to be kexec'ed.
> 
> The current code will fail to load a bzImage smaller than 32768 bytes (sizeof
> struct x86_linux_header), but the 'memdisk' program that comes with syslinux is
> only about 26 KiB.  This patch changes the minimum size to 1024 bytes (2
> sectors), which appears to be the limit that syslinux enforces.
> 
> Removed the "tail" field of struct x86_linux_header because it doesn't seem to
> actually be used (is there a reason for it?).
> 
> Also, note that bzImage_probe() was incorrectly using `sizeof (header)', even
> though header is a pointer.
> 
> Signed-off-by: Eric Biggers <ebiggers3@gmail.com>

Thanks, applied.

_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-06-13  1:33 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2012-06-01 15:59 [PATCH] Load bzImages smaller than 32 KiB Eric Biggers
2012-06-04 23:14 ` Simon Horman
2012-06-05 23:46   ` Eric Biggers
2012-06-13  1:33     ` Simon Horman

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