1 files changed, 59 insertions, 36 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 74e3658..431a0ed 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? */
@@ -124,7 +140,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin)
 {
 	loff_t retval;
 
-	lock_kernel();
+	mutex_lock(&file->f_dentry->d_inode->i_mutex);
 	switch (origin) {
 		case SEEK_END:
 			offset += i_size_read(file->f_path.dentry->d_inode);
@@ -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;
@@ -145,7 +161,7 @@ loff_t default_llseek(struct file *file, loff_t offset, int origin)
 		retval = offset;
 	}
 out:
-	unlock_kernel();
+	mutex_unlock(&file->f_dentry->d_inode->i_mutex);
 	return retval;
 }
 EXPORT_SYMBOL(default_llseek);
@@ -156,7 +172,6 @@ loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
 
 	fn = no_llseek;
 	if (file->f_mode & FMODE_LSEEK) {
-		fn = default_llseek;
 		if (file->f_op && file->f_op->llseek)
 			fn = file->f_op->llseek;
 	}
@@ -222,13 +237,12 @@ bad:
 }
 #endif
 
+
 /*
  * rw_verify_area doesn't like huge counts. We limit
  * them to something that fits in "int" so that others
  * won't have to do range checks all the time.
  */
-#define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
-
 int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
 {
 	struct inode *inode;
@@ -239,8 +253,11 @@ 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(
@@ -565,65 +582,71 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			      unsigned long nr_segs, unsigned long fast_segs,
 			      struct iovec *fast_pointer,
 			      struct iovec **ret_pointer)
-  {
+{
 	unsigned long seg;
-  	ssize_t ret;
+	ssize_t ret;
 	struct iovec *iov = fast_pointer;
 
-  	/*
-  	 * SuS says "The readv() function *may* fail if the iovcnt argument
-  	 * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
-  	 * traditionally returned zero for zero segments, so...
-  	 */
+	/*
+	 * SuS says "The readv() function *may* fail if the iovcnt argument
+	 * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
+	 * traditionally returned zero for zero segments, so...
+	 */
 	if (nr_segs == 0) {
 		ret = 0;
-  		goto out;
+		goto out;
 	}
 
-  	/*
-  	 * First get the "struct iovec" from user memory and
-  	 * verify all the pointers
-  	 */
+	/*
+	 * First get the "struct iovec" from user memory and
+	 * verify all the pointers
+	 */
 	if (nr_segs > UIO_MAXIOV) {
 		ret = -EINVAL;
-  		goto out;
+		goto out;
 	}
 	if (nr_segs > fast_segs) {
-  		iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
+		iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
 		if (iov == NULL) {
 			ret = -ENOMEM;
-  			goto out;
+			goto out;
 		}
-  	}
+	}
 	if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector))) {
 		ret = -EFAULT;
-  		goto out;
+		goto out;
 	}
 
-  	/*
+	/*
 	 * According to the Single Unix Specification we should return EINVAL
 	 * if an element length is < 0 when cast to ssize_t or if the
 	 * total length would overflow the ssize_t return value of the
 	 * system call.
-  	 */
+	 *
+	 * Linux caps all read/write calls to MAX_RW_COUNT, and avoids the
+	 * overflow case.
+	 */
 	ret = 0;
-  	for (seg = 0; seg < nr_segs; seg++) {
-  		void __user *buf = iov[seg].iov_base;
-  		ssize_t len = (ssize_t)iov[seg].iov_len;
+	for (seg = 0; seg < nr_segs; seg++) {
+		void __user *buf = iov[seg].iov_base;
+		ssize_t len = (ssize_t)iov[seg].iov_len;
 
 		/* see if we we're about to use an invalid len or if
 		 * it's about to overflow ssize_t */
-		if (len < 0 || (ret + len < ret)) {
+		if (len < 0) {
 			ret = -EINVAL;
-  			goto out;
+			goto out;
 		}
 		if (unlikely(!access_ok(vrfy_dir(type), buf, len))) {
 			ret = -EFAULT;
-  			goto out;
+			goto out;
+		}
+		if (len > MAX_RW_COUNT - ret) {
+			len = MAX_RW_COUNT - ret;
+			iov[seg].iov_len = len;
 		}
-
 		ret += len;
-  	}
+	}
 out:
 	*ret_pointer = iov;
 	return ret;