Messages in this thread Patch in this message | | | Date | Tue, 20 Feb 2007 17:50:21 -0800 | From | Greg KH <> | Subject | [patch 07/18] grow_buffers() infinite loop fix (CVE-2006-5757, CVE-2006-6060) |
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-stable review patch. If anyone has any objections, please let us know.
------------------ From: Andrew Morton <akpm@osdl.org>
If grow_buffers() is for some reason passed a block number which wants to lie outside the maximum-addressable pagecache range (PAGE_SIZE * 4G bytes) then it will accidentally truncate `index' and will then instnatiate a page at the wrong pagecache offset. This causes __getblk_slow() to go into an infinite loop.
This can happen with corrupted disks, or with software errors elsewhere.
Detect that, and handle it.
Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/buffer.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-)
--- linux-2.6.18.7.orig/fs/buffer.c +++ linux-2.6.18.7/fs/buffer.c @@ -1179,8 +1179,21 @@ grow_buffers(struct block_device *bdev, } while ((size << sizebits) < PAGE_SIZE); index = block >> sizebits; - block = index << sizebits; + /* + * Check for a block which wants to lie outside our maximum possible + * pagecache index. (this comparison is done using sector_t types). + */ + if (unlikely(index != block >> sizebits)) { + char b[BDEVNAME_SIZE]; + + printk(KERN_ERR "%s: requested out-of-range block %llu for " + "device %s\n", + __FUNCTION__, (unsigned long long)block, + bdevname(bdev, b)); + return -EIO; + } + block = index << sizebits; /* Create a page with the proper size buffers.. */ page = grow_dev_page(bdev, block, index, size); if (!page) @@ -1207,12 +1220,16 @@ __getblk_slow(struct block_device *bdev, for (;;) { struct buffer_head * bh; + int ret; bh = __find_get_block(bdev, block, size); if (bh) return bh; - if (!grow_buffers(bdev, block, size)) + ret = grow_buffers(bdev, block, size); + if (ret < 0) + return NULL; + if (ret == 0) free_more_memory(); } } -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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