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authorLinus Torvalds <torvalds@linux-foundation.org>2010-10-29 10:36:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-10-29 10:36:49 -0700
commit435f49a518c78eec8e2edbbadd912737246cbe20 (patch)
tree106df2617d42ace231e2fa9fcf1e0fd1075874ea /fs/compat.c
parentf56f44001cb5b40089deac094dbb74e5c9f64d81 (diff)
downloadlinux-435f49a518c78eec8e2edbbadd912737246cbe20.tar.gz
readv/writev: do the same MAX_RW_COUNT truncation that read/write does
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>
Diffstat (limited to 'fs/compat.c')
-rw-r--r--fs/compat.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/fs/compat.c b/fs/compat.c
index 52cfeb61da7..ff66c0d7583 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -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++;