linux-kernel - [PATCH 2/4] Squashfs: Update squashfs_readahead() to not use page->index

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240818235847.170468-3-phillip@squashfs.org.uk>
Date: Mon, 19 Aug 2024 00:58:45 +0100
From: Phillip Lougher <phillip@...ashfs.org.uk>
To: akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Cc: willy@...radead.org,
	lizetao1@...wei.com,
	Phillip Lougher <phillip@...ashfs.org.uk>
Subject: [PATCH 2/4] Squashfs: Update squashfs_readahead() to not use page->index

This commit removes references to page->index in the pages returned
from __readahead_batch(), and instead uses the 'start' variable.

This does reveal a bug in the previous code in that 'start' was
not updated every time around the loop.  This is fixed in this
commit.

Signed-off-by: Phillip Lougher <phillip@...ashfs.org.uk>
---
 fs/squashfs/file.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
index 2b6b63f4ccd1..50fe5a078b83 100644
--- a/fs/squashfs/file.c
+++ b/fs/squashfs/file.c
@@ -551,7 +551,6 @@ static void squashfs_readahead(struct readahead_control *ractl)
 		return;
 
 	for (;;) {
-		pgoff_t index;
 		int res, bsize;
 		u64 block = 0;
 		unsigned int expected;
@@ -570,13 +569,8 @@ static void squashfs_readahead(struct readahead_control *ractl)
 		if (readahead_pos(ractl) >= i_size_read(inode))
 			goto skip_pages;
 
-		index = pages[0]->index >> shift;
-
-		if ((pages[nr_pages - 1]->index >> shift) != index)
-			goto skip_pages;
-
-		if (index == file_end && squashfs_i(inode)->fragment_block !=
-						SQUASHFS_INVALID_BLK) {
+		if (start >> msblk->block_log == file_end &&
+				squashfs_i(inode)->fragment_block != SQUASHFS_INVALID_BLK) {
 			res = squashfs_readahead_fragment(pages, nr_pages,
 							  expected);
 			if (res)
@@ -584,7 +578,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
 			continue;
 		}
 
-		bsize = read_blocklist(inode, index, &block);
+		bsize = read_blocklist(inode, start >> msblk->block_log, &block);
 		if (bsize == 0)
 			goto skip_pages;
 
@@ -602,7 +596,7 @@ static void squashfs_readahead(struct readahead_control *ractl)
 
 			/* Last page (if present) may have trailing bytes not filled */
 			bytes = res % PAGE_SIZE;
-			if (index == file_end && bytes && last_page)
+			if (start >> msblk->block_log == file_end && bytes && last_page)
 				memzero_page(last_page, bytes,
 					     PAGE_SIZE - bytes);
 
@@ -616,6 +610,8 @@ static void squashfs_readahead(struct readahead_control *ractl)
 			unlock_page(pages[i]);
 			put_page(pages[i]);
 		}
+
+		start += readahead_batch_length(ractl);
 	}
 
 	kfree(pages);
-- 
2.39.2