1 files changed, 25 insertions, 9 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index a091ee4..df3468a 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -14,6 +14,7 @@
 #include <linux/security.h>
 #include <linux/module.h>
 #include <linux/syscalls.h>
+#include <linux/pagemap.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -182,22 +183,33 @@ 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;
 	loff_t pos;
 
-	if (unlikely(count > INT_MAX))
+	if (unlikely((ssize_t) count < 0))
 		goto Einval;
 	pos = *ppos;
 	if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
 		goto Einval;
 
 	inode = file->f_dentry->d_inode;
-	if (inode->i_flock && MANDATORY_LOCK(inode))
-		return locks_mandatory_area(read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE, inode, file, pos, count);
-	return 0;
+	if (inode->i_flock && MANDATORY_LOCK(inode)) {
+		int retval = locks_mandatory_area(
+			read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
+			inode, file, pos, count);
+		if (retval < 0)
+			return retval;
+	}
+	return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
 
 Einval:
 	return -EINVAL;
@@ -244,7 +256,8 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 		return -EFAULT;
 
 	ret = rw_verify_area(READ, file, pos, count);
-	if (!ret) {
+	if (ret >= 0) {
+		count = ret;
 		ret = security_file_permission (file, MAY_READ);
 		if (!ret) {
 			if (file->f_op->read)
@@ -295,7 +308,8 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
 		return -EFAULT;
 
 	ret = rw_verify_area(WRITE, file, pos, count);
-	if (!ret) {
+	if (ret >= 0) {
+		count = ret;
 		ret = security_file_permission (file, MAY_WRITE);
 		if (!ret) {
 			if (file->f_op->write)
@@ -497,7 +511,7 @@ static ssize_t do_readv_writev(int type, struct file *file,
 	}
 
 	ret = rw_verify_area(type, file, pos, tot_len);
-	if (ret)
+	if (ret < 0)
 		goto out;
 	ret = security_file_permission(file, type == READ ? MAY_READ : MAY_WRITE);
 	if (ret)
@@ -653,8 +667,9 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 		if (!(in_file->f_mode & FMODE_PREAD))
 			goto fput_in;
 	retval = rw_verify_area(READ, in_file, ppos, count);
-	if (retval)
+	if (retval < 0)
 		goto fput_in;
+	count = retval;
 
 	retval = security_file_permission (in_file, MAY_READ);
 	if (retval)
@@ -674,8 +689,9 @@ static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
 		goto fput_out;
 	out_inode = out_file->f_dentry->d_inode;
 	retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
-	if (retval)
+	if (retval < 0)
 		goto fput_out;
+	count = retval;
 
 	retval = security_file_permission (out_file, MAY_WRITE);
 	if (retval)