[PATCH] added sanity check for xattr validation

[PATCH] added sanity check for xattr validation

[Andreas Dilger]

Ted,
the attached patch adds an extra validity test in check_ext_attr().  If
an attribute's e_value_size is zero the current code does not allocate
a region for it and as a result the e_value_offs value is not verified.
However, if e_value_offs is very large then the later call to
ext2fs_ext_attr_hash_entry() can dereference bad memory and crash e2fsck.

Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: Jim Garlick <garlick@llnl.gov>

=========================== e_value_offs.patch ============================

Index: e2fsprogs-1.39/e2fsck/pass1.c
===================================================================
--- e2fsprogs-1.39.orig/e2fsck/pass1.c	2007-02-10 15:43:36.000000000 +0530
+++ e2fsprogs-1.39/e2fsck/pass1.c	2007-02-10 15:45:36.000000000 +0530
@@ -1346,6 +1347,11 @@
 			if (fix_problem(ctx, PR_1_EA_BAD_VALUE, pctx))
 				goto clear_extattr;
 		}
+		if (entry->e_value_offs + entry->e_value_size > fs->blocksize) {
+			if (fix_problem(ctx, PR_1_EA_BAD_VALUE, pctx))
+				goto clear_extattr;
+			break;
+		}
 		if (entry->e_value_size &&
 		    region_allocate(region, entry->e_value_offs,
 				    EXT2_EXT_ATTR_SIZE(entry->e_value_size))) {
=========================== e_value_offs.patch ============================

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

Re: [PATCH] added sanity check for xattr validation

[Eric Sandeen]

Andreas Dilger wrote:
> Ted,
> the attached patch adds an extra validity test in check_ext_attr().  If
> an attribute's e_value_size is zero the current code does not allocate
> a region for it and as a result the e_value_offs value is not verified.
> However, if e_value_offs is very large then the later call to
> ext2fs_ext_attr_hash_entry() can dereference bad memory and crash e2fsck.

Did this patch get lost?  Don't see it in Hg...

Thanks,
-Eric

> Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
> Signed-off-by: Jim Garlick <garlick@llnl.gov>
> 
> =========================== e_value_offs.patch ============================
> 
> Index: e2fsprogs-1.39/e2fsck/pass1.c
> ===================================================================
> --- e2fsprogs-1.39.orig/e2fsck/pass1.c	2007-02-10 15:43:36.000000000 +0530
> +++ e2fsprogs-1.39/e2fsck/pass1.c	2007-02-10 15:45:36.000000000 +0530
> @@ -1346,6 +1347,11 @@
>  			if (fix_problem(ctx, PR_1_EA_BAD_VALUE, pctx))
>  				goto clear_extattr;
>  		}
> +		if (entry->e_value_offs + entry->e_value_size > fs->blocksize) {
> +			if (fix_problem(ctx, PR_1_EA_BAD_VALUE, pctx))
> +				goto clear_extattr;
> +			break;
> +		}
>  		if (entry->e_value_size &&
>  		    region_allocate(region, entry->e_value_offs,
>  				    EXT2_EXT_ATTR_SIZE(entry->e_value_size))) {
> =========================== e_value_offs.patch ============================
> 
> Cheers, Andreas
> --
> Andreas Dilger
> Principal Software Engineer
> Cluster File Systems, Inc.
> 
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Re: [PATCH] added sanity check for xattr validation

[Theodore Tso]

On Thu, Jun 21, 2007 at 03:50:37PM -0500, Eric Sandeen wrote:
> Andreas Dilger wrote:
> > Ted,
> > the attached patch adds an extra validity test in check_ext_attr().  If
> > an attribute's e_value_size is zero the current code does not allocate
> > a region for it and as a result the e_value_offs value is not verified.
> > However, if e_value_offs is very large then the later call to
> > ext2fs_ext_attr_hash_entry() can dereference bad memory and crash e2fsck.
> 
> Did this patch get lost?  Don't see it in Hg...

Thanks, I just committed it.

						-Ted