Re: [PATCH] kexec/powerpc: Handle buffer overflow in kernel command line

[Zhang Yanfei <zhangyanfei.yes@gmail.com>]

Hello Suzuki,

Conflicts occur when I tried to apply the patch to latest kexec-tools by
using git am.

Applying: kexec/powerpc: Handle buffer overflow in kernel command line
/data/kexec-tools/.git/rebase-apply/patch:79: trailing whitespace.
		
error: patch failed: kexec/arch/ppc/kexec-elf-ppc.c:156
error: kexec/arch/ppc/kexec-elf-ppc.c: patch does not apply
error: patch failed: kexec/arch/ppc/kexec-uImage-ppc.c:81
error: kexec/arch/ppc/kexec-uImage-ppc.c: patch does not apply
Patch failed at 0001 kexec/powerpc: Handle buffer overflow in kernel command line
When you have resolved this problem run "git am --resolved".
If you would prefer to skip this patch, instead run "git am --skip".
To restore the original branch and stop patching run "git am --abort".

Thanks
Zhang

于 2013年04月02日 16:03, Suzuki K. Poulose 写道:
> From: Suzuki K. Poulose <suzuki@in.ibm.com>
> 
> Enforce size check for kernel command line to make sure it
> doesn't overflow COMMAND_LINE_SIZE.
> 
> Reported-by: Nathan D. Miller <nathanm2@us.ibm.com>
> Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
> ---
>  kexec/arch/ppc/kexec-elf-ppc.c    |   41 ++++++++++++++++++-------------------
>  kexec/arch/ppc/kexec-uImage-ppc.c |   31 ++++++++++++++--------------
>  2 files changed, 35 insertions(+), 37 deletions(-)
> 
> diff --git a/kexec/arch/ppc/kexec-elf-ppc.c b/kexec/arch/ppc/kexec-elf-ppc.c
> index 5f63a64..7ba8421 100644
> --- a/kexec/arch/ppc/kexec-elf-ppc.c
> +++ b/kexec/arch/ppc/kexec-elf-ppc.c
> @@ -156,7 +156,7 @@ int elf_ppc_load(int argc, char **argv,	const char *buf, off_t len,
>  {
>  	struct mem_ehdr ehdr;
>  	char *command_line, *crash_cmdline, *cmdline_buf;
> -	int command_line_len;
> +	int command_line_len, crash_cmdline_len;
>  	char *dtb;
>  	int result;
>  	unsigned long max_addr, hole_addr;
> @@ -233,27 +233,15 @@ int elf_ppc_load(int argc, char **argv,	const char *buf, off_t len,
>  	}
>  
>  	command_line_len = 0;
> -	if (command_line) {
> -		command_line_len = strlen(command_line) + 1;
> -	} else {
> +	if (!command_line)
>  		command_line = get_command_line();
> -		command_line_len = strlen(command_line) + 1;
> -	}
> +	command_line_len = strlen(command_line);
>  
>  	if (ramdisk && reuse_initrd)
>  		die("Can't specify --ramdisk or --initrd with --reuseinitrd\n");
>  
>  	fixup_nodes[cur_fixup] = NULL;
>  
> -	/* Need to append some command line parameters internally in case of
> -	 * taking crash dumps.
> -	 */
> -	if (info->kexec_flags & KEXEC_ON_CRASH) {
> -		crash_cmdline = xmalloc(COMMAND_LINE_SIZE);
> -		memset((void *)crash_cmdline, 0, COMMAND_LINE_SIZE);
> -	} else
> -		crash_cmdline = NULL;
> -
>  	/* Parse the Elf file */
>  	result = build_elf_exec_info(buf, len, &ehdr, 0);
>  	if (result < 0) {
> @@ -291,26 +279,37 @@ int elf_ppc_load(int argc, char **argv,	const char *buf, off_t len,
>  		return result;
>  	}
>  
> -	/* If panic kernel is being loaded, additional segments need
> -	 * to be created.
> +	/*
> +	 * Need to append some command line parameters internally in case of
> +	 * taking crash dumps. Additional segments have to be loaded for panic
> +	 * kernel.
>  	 */
>  	if (info->kexec_flags & KEXEC_ON_CRASH) {
> +		crash_cmdline = xmalloc(COMMAND_LINE_SIZE);
> +		memset((void *)crash_cmdline, 0, COMMAND_LINE_SIZE);
>  		result = load_crashdump_segments(info, crash_cmdline,
>  						max_addr, 0);
>  		if (result < 0) {
>  			free(crash_cmdline);
>  			return -1;
>  		}
> +		crash_cmdline_len = strlen(crash_cmdline);
> +	} else {
> +		crash_cmdline = NULL;
> +		crash_cmdline_len = 0;
>  	}
>  
> +	if (crash_cmdline_len + command_line_len + 1 > COMMAND_LINE_SIZE) {
> +		printf ("Command line buffer overflow\n");
> +		return -1;
> +	}
> +		
>  	cmdline_buf = xmalloc(COMMAND_LINE_SIZE);
>  	memset((void *)cmdline_buf, 0, COMMAND_LINE_SIZE);
>  	if (command_line)
> -		strncat(cmdline_buf, command_line, command_line_len);
> +		strcpy(cmdline_buf, command_line);
>  	if (crash_cmdline)
> -		strncat(cmdline_buf, crash_cmdline,
> -				sizeof(crash_cmdline) -
> -				strlen(crash_cmdline) - 1);
> +		strncat(cmdline_buf, crash_cmdline, crash_cmdline_len);
>  
>  	/*
>  	 * In case of a toy we take the hardcoded things and an easy setup via
> diff --git a/kexec/arch/ppc/kexec-uImage-ppc.c b/kexec/arch/ppc/kexec-uImage-ppc.c
> index 900cd16..0c96bac 100644
> --- a/kexec/arch/ppc/kexec-uImage-ppc.c
> +++ b/kexec/arch/ppc/kexec-uImage-ppc.c
> @@ -81,7 +81,7 @@ static int ppc_load_bare_bits(int argc, char **argv, const char *buf,
>  		unsigned int ep)
>  {
>  	char *command_line, *cmdline_buf, *crash_cmdline;
> -	int command_line_len;
> +	int command_line_len, crash_cmdline_len;
>  	char *dtb;
>  	unsigned int addr;
>  	unsigned long dtb_addr;
> @@ -140,13 +140,10 @@ static int ppc_load_bare_bits(int argc, char **argv, const char *buf,
>  		die("Can't specify --ramdisk or --initrd with --reuseinitrd\n");
>  
>  	command_line_len = 0;
> -	if (command_line) {
> -		command_line_len = strlen(command_line) + 1;
> -	} else {
> +	if (!command_line)
>  		command_line = get_command_line();
> -		command_line_len = strlen(command_line) + 1;
> -	}
>  
> +	command_line_len = strlen(command_line);
>  	fixup_nodes[cur_fixup] = NULL;
>  
>  	/*
> @@ -179,25 +176,27 @@ static int ppc_load_bare_bits(int argc, char **argv, const char *buf,
>  	if (info->kexec_flags & KEXEC_ON_CRASH) {
>                  crash_cmdline = xmalloc(COMMAND_LINE_SIZE);
>                  memset((void *)crash_cmdline, 0, COMMAND_LINE_SIZE);
> -        } else
> -                crash_cmdline = NULL;
> -
> -	if (info->kexec_flags & KEXEC_ON_CRASH) {
>  		ret = load_crashdump_segments(info, crash_cmdline,
>  						max_addr, 0);
> -		if (ret < 0) {
> +		if (ret < 0)
>  			return -1;
> -		}
> +		crash_cmdline_len = strlen(crash_cmdline);
> +	} else {
> +		crash_cmdline = NULL;
> +		crash_cmdline_len = 0;
> +	}
> +
> +	if (command_line_len + crash_cmdline_len + 1 > COMMAND_LINE_SIZE) {
> +		printf("Command line buffer overflow \n");
> +		return -1;
>  	}
>  
>  	cmdline_buf = xmalloc(COMMAND_LINE_SIZE);
>  	memset((void *)cmdline_buf, 0, COMMAND_LINE_SIZE);
>  	if (command_line)
> -		strncat(cmdline_buf, command_line, command_line_len);
> +		strcpy(cmdline_buf, command_line);
>  	if (crash_cmdline)
> -		strncat(cmdline_buf, crash_cmdline,
> -			sizeof(crash_cmdline) -
> -			strlen(crash_cmdline) - 1);
> +		strncat(cmdline_buf, crash_cmdline, crash_cmdline_len);
>  
>  	elf_rel_build_load(info, &info->rhdr, (const char *)purgatory,
>  				purgatory_size, 0, -1, -1, 0);
> 
> 
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