lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

readv/writev: do the same MAX_RW_COUNT truncation that read/write does

Browse Source 
We used to protect against overflow, but rather than return an error, do
what read/write does, namely to limit the total size to MAX_RW_COUNT.
This is not only more consistent, but it also means that any broken
low-level read/write routine that still keeps counts in 'int' can't
break.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds
2010-10-29 10:36:49 -07:00
parent f56f44001c
commit 435f49a518
3 changed files with 40 additions and 35 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
fs/compat.c
View File

@@ -606,14 +606,14 @@ ssize_t compat_rw_copy_check_uvector(int type,
/*
* Single unix specification:
* We should -EINVAL if an element length is not >= 0 and fitting an
* ssize_t. The total length is fitting an ssize_t
* ssize_t.
*
* Be careful here because iov_len is a size_t not an ssize_t
* In Linux, the total length is limited to MAX_RW_COUNT, there is
* no overflow possibility.
*/
tot_len = 0;
ret = -EINVAL;
for (seg = 0; seg < nr_segs; seg++) {
compat_ssize_t tmp = tot_len;
compat_uptr_t buf;
compat_ssize_t len;
@@ -624,13 +624,13 @@ ssize_t compat_rw_copy_check_uvector(int type,
}
if (len < 0) /* size_t not fitting in compat_ssize_t .. */
goto out;
tot_len += len;
if (tot_len < tmp) /* maths overflow on the compat_ssize_t */
goto out;
if (!access_ok(vrfy_dir(type), compat_ptr(buf), len)) {
ret = -EFAULT;
goto out;
}
if (len > MAX_RW_COUNT - tot_len)
len = MAX_RW_COUNT - tot_len;
tot_len += len;
iov->iov_base = compat_ptr(buf);
iov->iov_len = (compat_size_t) len;
uvector++;