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CVE-2016-4913 isofs: info leak with malformed NM entries (rhbz 1337528 1337529)

This commit is contained in:
Josh Boyer 2016-05-19 08:08:00 -04:00
parent 35e58915f0
commit 2b03673893
2 changed files with 69 additions and 0 deletions
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63
get_rock_ridge_filename-handle-malformed-NM-entries.patch Normal file
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@ -0,0 +1,63 @@
From 99d825822eade8d827a1817357cbf3f889a552d6 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Thu, 5 May 2016 16:25:35 -0400
Subject: [PATCH] get_rock_ridge_filename(): handle malformed NM entries
Payloads of NM entries are not supposed to contain NUL. When we run
into such, only the part prior to the first NUL goes into the
concatenation (i.e. the directory entry name being encoded by a bunch
of NM entries). We do stop when the amount collected so far + the
claimed amount in the current NM entry exceed 254. So far, so good,
but what we return as the total length is the sum of *claimed*
sizes, not the actual amount collected. And that can grow pretty
large - not unlimited, since you'd need to put CE entries in
between to be able to get more than the maximum that could be
contained in one isofs directory entry / continuation chunk and
we are stop once we'd encountered 32 CEs, but you can get about 8Kb
easily. And that's what will be passed to readdir callback as the
name length. 8Kb __copy_to_user() from a buffer allocated by
__get_free_page()
Cc: stable@vger.kernel.org # 0.98pl6+ (yes, really)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/isofs/rock.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/fs/isofs/rock.c b/fs/isofs/rock.c
index 5384ceb35b1c..98b3eb7d8eaf 100644
--- a/fs/isofs/rock.c
+++ b/fs/isofs/rock.c
@@ -203,6 +203,8 @@ int get_rock_ridge_filename(struct iso_directory_record *de,
int retnamlen = 0;
int truncate = 0;
int ret = 0;
+ char *p;
+ int len;
if (!ISOFS_SB(inode->i_sb)->s_rock)
return 0;
@@ -267,12 +269,17 @@ repeat:
rr->u.NM.flags);
break;
}
- if ((strlen(retname) + rr->len - 5) >= 254) {
+ len = rr->len - 5;
+ if (retnamlen + len >= 254) {
truncate = 1;
break;
}
- strncat(retname, rr->u.NM.name, rr->len - 5);
- retnamlen += rr->len - 5;
+ p = memchr(rr->u.NM.name, '\0', len);
+ if (unlikely(p))
+ len = p - rr->u.NM.name;
+ memcpy(retname + retnamlen, rr->u.NM.name, len);
+ retnamlen += len;
+ retname[retnamlen] = '\0';
break;
case SIG('R', 'E'):
kfree(rs.buffer);
--
2.5.5

6
kernel.spec
View File

@ -669,6 +669,9 @@ Patch717: KEYS-Fix-ASN.1-indefinite-length-object-parsing.patch
#CVE-2016-3713 rhbz 1332139 1336410
Patch718: KVM-MTRR-remove-MSR-0x2f8.patch
#CVE-2016-4913 rhbz 1337528 1337529
Patch719: get_rock_ridge_filename-handle-malformed-NM-entries.patch
# END OF PATCH DEFINITIONS
%endif
@ -2190,6 +2193,9 @@ fi
#
#
%changelog
* Thu May 19 2016 Josh Boyer <jwboyer@fedoraproject.org>
- CVE-2016-4913 isofs: info leak with malformed NM entries (rhbz 1337528 1337529)
* Mon May 16 2016 Justin M. Forbes <jforbes@fedoraproject.org>
- Disable CONFIG_DEBUG_VM_PGFLAGS on non debug kernels (rhbz 1335173)