The patch titled
Subject: reiserfs: fix broken xattr handling (heap corruption, bad retval)
has been added to the -mm tree. Its filename is
reiserfs-fix-broken-xattr-handling-heap-corruption-bad-retval.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/reiserfs-fix-broken-xattr-handling-heap-corruption-bad-retval.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/reiserfs-fix-broken-xattr-handling-heap-corruption-bad-retval.patch
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------------------------------------------------------
From: Jann Horn <jannh@xxxxxxxxxx>
Subject: reiserfs: fix broken xattr handling (heap corruption, bad retval)
This fixes the following issues:
- When a buffer size is supplied to reiserfs_listxattr() such that each
individual name fits, but the concatenation of all names doesn't fit,
reiserfs_listxattr() overflows the supplied buffer. This leads to a
kernel heap overflow (verified using KASAN) followed by an out-of-bounds
usercopy and is therefore a security bug.
- When a buffer size is supplied to reiserfs_listxattr() such that a
name doesn't fit, -ERANGE should be returned. But reiserfs instead just
truncates the list of names; I have verified that if the only xattr on a
file has a longer name than the supplied buffer length, listxattr()
incorrectly returns zero.
With my patch applied, -ERANGE is returned in both cases and the memory
corruption doesn't happen anymore.
Credit for making me clean this code up a bit goes to Al Viro, who pointed
out that the ->actor calling convention is suboptimal and should be
changed.
Link: http://lkml.kernel.org/r/20180802151539.5373-1-jannh@xxxxxxxxxx
Fixes: 48b32a3553a5 ("reiserfs: use generic xattr handlers")
Signed-off-by: Jann Horn <jannh@xxxxxxxxxx>
Cc: Jeff Mahoney <jeffm@xxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/reiserfs/xattr.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/fs/reiserfs/xattr.c~reiserfs-fix-broken-xattr-handling-heap-corruption-bad-retval
+++ a/fs/reiserfs/xattr.c
@@ -792,8 +792,10 @@ static int listxattr_filler(struct dir_c
return 0;
size = namelen + 1;
if (b->buf) {
- if (size > b->size)
+ if (b->pos + size > b->size) {
+ b->pos = -ERANGE;
return -ERANGE;
+ }
memcpy(b->buf + b->pos, name, namelen);
b->buf[b->pos + namelen] = 0;
}
_
Patches currently in -mm which might be from jannh@xxxxxxxxxx are
reiserfs-fix-broken-xattr-handling-heap-corruption-bad-retval.patch
fork-dont-copy-inconsistent-signal-handler-state-to-child.patch
