linux-kernel - Re: [PATCH v4 2/4] tools/bootconfig: Fix to check the write failure correctly

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 19 Nov 2020 14:42:41 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Chen Yu <yu.c.chen@...el.com>,
        Chen Yu <yu.chen.surf@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH v4 2/4] tools/bootconfig: Fix to check the write failure
 correctly

On Thu, 19 Nov 2020 00:35:35 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:

> Fix to check the write(2) failure including partial write
> correctly and try to rollback the partial write, because
> if there is no BOOTCONFIG_MAGIC string, we can not remove it.
> 
> Fixes: 85c46b78da58 ("bootconfig: Add bootconfig magic word for indicating bootconfig explicitly")
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> Tested-by: Chen Yu <yu.chen.surf@...il.com>
> ---
>  tools/bootconfig/main.c |   27 +++++++++++++++++++++++----
>  1 file changed, 23 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
> index 52eb2bbe8966..905bfaefae35 100644
> --- a/tools/bootconfig/main.c
> +++ b/tools/bootconfig/main.c
> @@ -337,6 +337,7 @@ static int delete_xbc(const char *path)
>  
>  static int apply_xbc(const char *path, const char *xbc_path)
>  {
> +	struct stat stat;
>  	u32 size, csum;
>  	char *buf, *data;
>  	int ret, fd;
> @@ -394,16 +395,26 @@ static int apply_xbc(const char *path, const char *xbc_path)
>  		return ret;
>  	}
>  	/* TODO: Ensure the @path is initramfs/initrd image */
> +	if (fstat(fd, &stat) < 0) {
> +		pr_err("Failed to get the size of %s\n", path);
> +		goto out;
> +	}
>  	ret = write(fd, data, size + 8);
> -	if (ret < 0) {
> +	if (ret < size + 8) {
> +		if (ret < 0)
> +			ret = -errno;
>  		pr_err("Failed to apply a boot config: %d\n", ret);
> -		goto out;
> +		if (ret < 0)
> +			goto out;
> +		goto out_rollback;
>  	}
>  	/* Write a magic word of the bootconfig */
>  	ret = write(fd, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
> -	if (ret < 0) {
> +	if (ret < BOOTCONFIG_MAGIC_LEN) {
> +		if (ret < 0)
> +			ret = -errno;
>  		pr_err("Failed to apply a boot config magic: %d\n", ret);
> -		goto out;
> +		goto out_rollback;
>  	}
>  	ret = 0;
>  out:
> @@ -411,6 +422,14 @@ static int apply_xbc(const char *path, const char *xbc_path)
>  	free(data);
>  
>  	return ret;
> +
> +out_rollback:

Oops, I forgot to set error to return value here.

I'll fix that.

Thank you,

> +	if (ftruncate(fd, stat.st_size) < 0) {
> +		ret = -errno;
> +		pr_err("Failed to rollback the write error: %d\n", ret);
> +		pr_err("The initrd %s may be corrupted. Recommend to rebuild.\n", path);
> +	}
> +	goto out;
>  }
>  
>  static int usage(void)
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>