On 2/13/07, Andrew Morton <[email protected]> wrote:
> On Tue, 13 Feb 2007 17:55:31 -0600 Eric Van Hensbergen <[email protected]> wrote:
> +int v9fs_prepare_write(struct file *file, struct page *page,
> + unsigned from, unsigned to)
> +{
> + if (!PageUptodate(page)) {
> + if (to - from != PAGE_CACHE_SIZE) {
> + void *kaddr = kmap_atomic(page, KM_USER0);
> + memset(kaddr, 0, from);
> + memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
> + flush_dcache_page(page);
> + kunmap_atomic(kaddr, KM_USER0);
> + }
> + SetPageUptodate(page);
> + }
This will mark the page uptodate while the piece between `to' and `from' is
uninitialised. A concurrent pagefault can come in and permit a read of
that uninitialised data. Because filemap_nopage() doesn't lock the page if
it is uptodate.
Okay - I snagged this code from fs/libfs.c (simple_prepare_write) --
is that code also not correct, or am I just using it in the wrong
context?
-eric
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
