This is a note to let you know that I've just added the patch titled
udf: Avoid infinite loop when processing indirect ICBs
to the 3.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
udf-avoid-infinite-loop-when-processing-indirect-icbs.patch
and it can be found in the queue-3.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c03aa9f6e1f938618e6db2e23afef0574efeeb65 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@xxxxxxx>
Date: Thu, 4 Sep 2014 14:06:55 +0200
Subject: udf: Avoid infinite loop when processing indirect ICBs
From: Jan Kara <jack@xxxxxxx>
commit c03aa9f6e1f938618e6db2e23afef0574efeeb65 upstream.
We did not implement any bound on number of indirect ICBs we follow when
loading inode. Thus corrupted medium could cause kernel to go into an
infinite loop, possibly causing a stack overflow.
Fix the possible stack overflow by removing recursion from
__udf_read_inode() and limit number of indirect ICBs we follow to avoid
infinite loops.
Signed-off-by: Jan Kara <jack@xxxxxxx>
Cc: Chuck Ebbert <cebbert.lkml@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/udf/inode.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)
--- a/fs/udf/inode.c
+++ b/fs/udf/inode.c
@@ -1271,13 +1271,22 @@ update_time:
return 0;
}
+/*
+ * Maximum length of linked list formed by ICB hierarchy. The chosen number is
+ * arbitrary - just that we hopefully don't limit any real use of rewritten
+ * inode on write-once media but avoid looping for too long on corrupted media.
+ */
+#define UDF_MAX_ICB_NESTING 1024
+
static void __udf_read_inode(struct inode *inode)
{
struct buffer_head *bh = NULL;
struct fileEntry *fe;
uint16_t ident;
struct udf_inode_info *iinfo = UDF_I(inode);
+ unsigned int indirections = 0;
+reread:
/*
* Set defaults, but the inode is still incomplete!
* Note: get_new_inode() sets the following on a new inode:
@@ -1314,28 +1323,26 @@ static void __udf_read_inode(struct inod
ibh = udf_read_ptagged(inode->i_sb, &iinfo->i_location, 1,
&ident);
if (ident == TAG_IDENT_IE && ibh) {
- struct buffer_head *nbh = NULL;
struct kernel_lb_addr loc;
struct indirectEntry *ie;
ie = (struct indirectEntry *)ibh->b_data;
loc = lelb_to_cpu(ie->indirectICB.extLocation);
- if (ie->indirectICB.extLength &&
- (nbh = udf_read_ptagged(inode->i_sb, &loc, 0,
- &ident))) {
- if (ident == TAG_IDENT_FE ||
- ident == TAG_IDENT_EFE) {
- memcpy(&iinfo->i_location,
- &loc,
- sizeof(struct kernel_lb_addr));
- brelse(bh);
- brelse(ibh);
- brelse(nbh);
- __udf_read_inode(inode);
+ if (ie->indirectICB.extLength) {
+ brelse(bh);
+ brelse(ibh);
+ memcpy(&iinfo->i_location, &loc,
+ sizeof(struct kernel_lb_addr));
+ if (++indirections > UDF_MAX_ICB_NESTING) {
+ udf_err(inode->i_sb,
+ "too many ICBs in ICB hierarchy"
+ " (max %d supported)\n",
+ UDF_MAX_ICB_NESTING);
+ make_bad_inode(inode);
return;
}
- brelse(nbh);
+ goto reread;
}
}
brelse(ibh);
Patches currently in stable-queue which might be from jack@xxxxxxx are
queue-3.16/udf-avoid-infinite-loop-when-processing-indirect-icbs.patch
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