| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20090917155100.3cc2dfb6.kamezawa.hiroyu@jp.fujitsu.com>
Date: Thu, 17 Sep 2009 15:51:00 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: Wu Fengguang <fengguang.wu@...el.com>
Cc: "viro@...iv.linux.org.uk" <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"hugh.dickins@...cali.co.uk" <hugh.dickins@...cali.co.uk>,
"oleg@...hat.com" <oleg@...hat.com>,
"xiyou.wangcong@...il.com" <xiyou.wangcong@...il.com>
Subject: [RFC][PATCH][bugfix] more checks for negative f_pos handling v4
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Now, rw_verify_area() checsk f_pos is negative or not. And if
negative, returns -EINVAL.
But, some special files as /dev/(k)mem and /proc/<pid>/mem etc..
has negative offsets. And we can't do any access via read/write
to the file(device).
This patch introduce a flag S_VERYBIG and allow negative file
offsets for big files. (usual files don't allow it.)
Changelog: v3->v4
- make changes in mem.c aligned.
- change __negative_fpos_check() to return int.
- fixed bug in "pos" check.
- added comments.
Changelog: v2->v3
- fixed bug in rw_verify_area (it cannot be compiled)
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
drivers/char/mem.c | 23 +++++++++++++----------
fs/proc/base.c | 2 ++
fs/read_write.c | 22 ++++++++++++++++++++--
include/linux/fs.h | 2 ++
4 files changed, 37 insertions(+), 12 deletions(-)
Index: mmotm-2.6.31-Sep14/fs/read_write.c
===================================================================
--- mmotm-2.6.31-Sep14.orig/fs/read_write.c
+++ mmotm-2.6.31-Sep14/fs/read_write.c
@@ -205,6 +205,21 @@ bad:
}
#endif
+static int
+__negative_fpos_check(struct inode *inode, loff_t pos, size_t count)
+{
+ /*
+ * pos or pos+count is negative here, check overflow.
+ * too big "count" will be caught in rw_verify_area().
+ */
+ if ((pos < 0) && (pos + count < pos))
+ return -EOVERFLOW;
+ /* If !VERYBIG inode, negative pos(pos+count) is not allowed */
+ if (!IS_VERYBIG(inode))
+ return -EINVAL;
+ return 0;
+}
+
/*
* rw_verify_area doesn't like huge counts. We limit
* them to something that fits in "int" so that others
@@ -222,8 +237,11 @@ int rw_verify_area(int read_write, struc
if (unlikely((ssize_t) count < 0))
return retval;
pos = *ppos;
- if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
- return retval;
+ if (unlikely((pos < 0) || (loff_t) (pos + count) < 0)) {
+ retval = __negative_fpos_check(inode, pos, count);
+ if (retval)
+ return retval;
+ }
if (unlikely(inode->i_flock && mandatory_lock(inode))) {
retval = locks_mandatory_area(
Index: mmotm-2.6.31-Sep14/include/linux/fs.h
===================================================================
--- mmotm-2.6.31-Sep14.orig/include/linux/fs.h
+++ mmotm-2.6.31-Sep14/include/linux/fs.h
@@ -231,6 +231,7 @@ struct inodes_stat_t {
#define S_NOCMTIME 128 /* Do not update file c/mtime */
#define S_SWAPFILE 256 /* Do not truncate: swapon got its bmaps */
#define S_PRIVATE 512 /* Inode is fs-internal */
+#define S_VERYBIG 1024 /* Allow file's loff_t can be negative */
/*
* Note that nosuid etc flags are inode-specific: setting some file-system
@@ -265,6 +266,7 @@ struct inodes_stat_t {
#define IS_NOCMTIME(inode) ((inode)->i_flags & S_NOCMTIME)
#define IS_SWAPFILE(inode) ((inode)->i_flags & S_SWAPFILE)
#define IS_PRIVATE(inode) ((inode)->i_flags & S_PRIVATE)
+#define IS_VERYBIG(inode) ((inode)->i_flags & S_VERYBIG)
/* the read-only stuff doesn't really belong here, but any other place is
probably as bad and I don't want to create yet another include file. */
Index: mmotm-2.6.31-Sep14/drivers/char/mem.c
===================================================================
--- mmotm-2.6.31-Sep14.orig/drivers/char/mem.c
+++ mmotm-2.6.31-Sep14/drivers/char/mem.c
@@ -825,22 +825,23 @@ static const struct memdev {
const char *name;
const struct file_operations *fops;
struct backing_dev_info *dev_info;
+ bool verybig;
} devlist[] = {
- [ 1] = { "mem", &mem_fops, &directly_mappable_cdev_bdi },
+ [1] = { "mem", &mem_fops, &directly_mappable_cdev_bdi, true },
#ifdef CONFIG_DEVKMEM
- [ 2] = { "kmem", &kmem_fops, &directly_mappable_cdev_bdi },
+ [2] = { "kmem", &kmem_fops, &directly_mappable_cdev_bdi, true },
#endif
- [ 3] = {"null", &null_fops, NULL },
+ [3] = {"null", &null_fops, NULL, false },
#ifdef CONFIG_DEVPORT
- [ 4] = { "port", &port_fops, NULL },
+ [4] = { "port", &port_fops, NULL, false },
#endif
- [ 5] = { "zero", &zero_fops, &zero_bdi },
- [ 6] = { "full", &full_fops, NULL },
- [ 7] = { "random", &random_fops, NULL },
- [ 9] = { "urandom", &urandom_fops, NULL },
- [11] = { "kmsg", &kmsg_fops, NULL },
+ [5] = { "zero", &zero_fops, &zero_bdi, false },
+ [6] = { "full", &full_fops, NULL, false },
+ [7] = { "random", &random_fops, NULL, false },
+ [9] = { "urandom", &urandom_fops, NULL, false },
+ [11] = { "kmsg", &kmsg_fops, NULL, false },
#ifdef CONFIG_CRASH_DUMP
- [12] = { "oldmem", &oldmem_fops, NULL },
+ [12] = { "oldmem", &oldmem_fops, NULL, false },
#endif
};
@@ -868,6 +869,8 @@ static int memory_open(struct inode *ino
ret = dev->fops->open(inode, filp);
else
ret = 0;
+ if (dev->verybig)
+ inode->i_flags |= S_VERYBIG;
out:
unlock_kernel();
return ret;
Index: mmotm-2.6.31-Sep14/fs/proc/base.c
===================================================================
--- mmotm-2.6.31-Sep14.orig/fs/proc/base.c
+++ mmotm-2.6.31-Sep14/fs/proc/base.c
@@ -779,6 +779,8 @@ static const struct file_operations proc
static int mem_open(struct inode* inode, struct file* file)
{
file->private_data = (void*)((long)current->self_exec_id);
+ /* this file is read only and we can catch out-pf-range */
+ inode->i_flags |= S_VERYBIG;
return 0;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists