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-rw-r--r--fs/read_write.c34
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)
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