Re: [ 046/180] xfs: Fix possible memory corruption in xfs_readlink

[Herton Ronaldo Krzesinski]

On Tue, Oct 02, 2012 at 12:52:43AM +0200, Willy Tarreau wrote:
> 2.6.32-longterm review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Carlos Maiolino <cmaiolino@xxxxxxxxxx>
> 
> commit b52a360b2aa1c59ba9970fb0f52bbb093fcc7a24 upstream
> 
[...]
> @@ -564,13 +564,20 @@ xfs_readlink(
>  
>  	xfs_ilock(ip, XFS_ILOCK_SHARED);
>  
> -	ASSERT((ip->i_d.di_mode & S_IFMT) == S_IFLNK);
> -	ASSERT(ip->i_d.di_size <= MAXPATHLEN);
> -
>  	pathlen = ip->i_d.di_size;
>  	if (!pathlen)
>  		goto out;
>  
> +	if (pathlen < 0 || pathlen > MAXPATHLEN) {
> +		xfs_fs_cmn_err(CE_ALERT, mp,
> +			 "%s: inode (%llu) bad symlink length (%lld)",
> +			 __func__, (unsigned long long) ip->i_ino,
> +			 (long long) pathlen);
> +		ASSERT(0);
> +		return XFS_ERROR(EFSCORRUPTED);

This needs a followup fix, commit 9b025eb3a89e041bab6698e3858706be2385d692
("xfs: Fix missing xfs_iunlock() on error recovery path in xfs_readlink()").
I think it should be also cherry-picked in this release.

> +	}
> +
> +
>  	if (ip->i_df.if_flags & XFS_IFINLINE) {
>  		memcpy(link, ip->i_df.if_u1.if_data, pathlen);
>  		link[pathlen] = '\0';

-- 
[]'s
Herton
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