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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2010-10-01 14:20:22 -0700
committerAl Viro <viro@zeniv.linux.org.uk>2010-10-25 21:18:21 -0400
commit4a3956c790290efeb647bbb0c3a90476bb57800e (patch)
tree18abb41325273d23ae271e49627f01054c5baeb6 /fs/read_write.c
parentba10f486658c0ca1bc84c936f6a996e40d071453 (diff)
downloadlinux-4a3956c790290efeb647bbb0c3a90476bb57800e.tar.gz
vfs: introduce FMODE_UNSIGNED_OFFSET for allowing negative f_pos
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). So introduce FMODE_UNSIGNED_OFFSET to allow negative file offsets. Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/read_write.c')
-rw-r--r--fs/read_write.c28
1 files changed, 24 insertions, 4 deletions
diff --git a/fs/read_write.c b/fs/read_write.c
index e757ef26e4c..9cd9d148105 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -31,6 +31,20 @@ const struct file_operations generic_ro_fops = {
EXPORT_SYMBOL(generic_ro_fops);
+static int
+__negative_fpos_check(struct file *file, 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 (file->f_mode & FMODE_UNSIGNED_OFFSET)
+ return 0;
+ return -EINVAL;
+}
+
/**
* generic_file_llseek_unlocked - lockless generic llseek implementation
* @file: file structure to seek on
@@ -62,7 +76,9 @@ generic_file_llseek_unlocked(struct file *file, loff_t offset, int origin)
break;
}
- if (offset < 0 || offset > inode->i_sb->s_maxbytes)
+ if (offset < 0 && __negative_fpos_check(file, offset, 0))
+ return -EINVAL;
+ if (offset > inode->i_sb->s_maxbytes)
return -EINVAL;
/* Special lock needed here? */
@@ -137,7 +153,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin)
offset += file->f_pos;
}
retval = -EINVAL;
- if (offset >= 0) {
+ if (offset >= 0 || !__negative_fpos_check(file, offset, 0)) {
if (offset != file->f_pos) {
file->f_pos = offset;
file->f_version = 0;
@@ -221,6 +237,7 @@ bad:
}
#endif
+
/*
* rw_verify_area doesn't like huge counts. We limit
* them to something that fits in "int" so that others
@@ -238,8 +255,11 @@ int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count
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(file, pos, count);
+ if (retval)
+ return retval;
+ }
if (unlikely(inode->i_flock && mandatory_lock(inode))) {
retval = locks_mandatory_area(