On Tue, 2006-12-19 at 09:43 -0800, Linus Torvalds wrote:
>
> Btw,
> here's a totally new tangent on this: it's possible that user code is
> simply BUGGY.
depmod: BADNESS: written outside isize 22183
---
diff --git a/fs/buffer.c b/fs/buffer.c
index d1f1b54..5db9fd9 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2393,6 +2393,17 @@ int nobh_commit_write(struct file *file, struct page
*page,
}
EXPORT_SYMBOL(nobh_commit_write);
+static void __check_tail_zero(char *kaddr, unsigned int offset)
+{
+ unsigned int check = 0;
+ do {
+ check += kaddr[offset++];
+ } while (offset < PAGE_CACHE_SIZE);
+ if (check)
+ printk(KERN_ERR "%s: BADNESS: written outside isize %u\n",
+ current->comm, check);
+}
+
/*
* nobh_writepage() - based on block_full_write_page() except
* that it tries to operate without attaching bufferheads to
@@ -2437,6 +2448,7 @@ int nobh_writepage(struct page *page, get_block_t
*get_block,
* writes to that region are not written out to the file."
*/
kaddr = kmap_atomic(page, KM_USER0);
+ __check_tail_zero(kaddr, offset);
memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
@@ -2604,6 +2616,7 @@ int block_write_full_page(struct page *page, get_block_t
*get_block,
* writes to that region are not written out to the file."
*/
kaddr = kmap_atomic(page, KM_USER0);
+ __check_tail_zero(kaddr, offset);
memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
-
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