linux-ext4 - Re: [PATCH] filefrag: avoid temporary buffer overflow

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Date:   Fri, 2 Mar 2018 09:48:28 -0800
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Andreas Dilger <andreas.dilger@...el.com>
Cc:     tytso@....edu, linux-ext4@...r.kernel.org,
        Andreas Dilger <adilger@...ger.ca>
Subject: Re: [PATCH] filefrag: avoid temporary buffer overflow

On Thu, Mar 01, 2018 at 01:09:46PM -0700, Andreas Dilger wrote:
> From: Andreas Dilger <adilger@...ger.ca>
> 
> If an unknown flag is present in a FIEMAP extent, it is printed as a
> hex value into a temporary buffer before adding it to the flags.  If
> that unknown flag is over 0xffff then it will overflow the temporary
> buffer.
> 
> Reported-by: Sarah Liu <wei3.liu@...el.com>
> Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-10335
> Signed-off-by: Andreas Dilger <andreas.dilger@...el.com>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@...cle.com>

--D

> ---
>  misc/filefrag.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/misc/filefrag.c b/misc/filefrag.c
> index 9c57ab9..dc00393 100644
> --- a/misc/filefrag.c
> +++ b/misc/filefrag.c
> @@ -179,7 +179,7 @@ static void print_extent_info(struct fiemap_extent *fm_extent, int cur_ex,
>  	print_flag(&fe_flags, FIEMAP_EXTENT_SHARED, flags, "shared,");
>  	/* print any unknown flags as hex values */
>  	for (mask = 1; fe_flags != 0 && mask != 0; mask <<= 1) {
> -		char hex[6];
> +		char hex[sizeof(mask) * 2 + 4]; /* 2 chars/byte + 0x, + NUL */
>  
>  		if ((fe_flags & mask) == 0)
>  			continue;
> -- 
> 1.8.0
>