From bc5c48ac0177db44663c900eb19debc959fd447a Mon Sep 17 00:00:00 2001
From: Chunhai Guo <guochunhai@vivo.com>
Date: Mon, 10 Jul 2023 17:34:10 +0800
Subject: [PATCH] erofs: avoid infinite loop in z_erofs_do_read_page() when
reading beyond EOF
[ Upstream commit 8191213a5835b0317c5e4d0d337ae1ae00c75253 ]
z_erofs_do_read_page() may loop infinitely due to the inappropriate
truncation in the below statement. Since the offset is 64 bits and min_t()
truncates the result to 32 bits. The solution is to replace unsigned int
with a 64-bit type, such as erofs_off_t.
cur = end - min_t(unsigned int, offset + end - map->m_la, end);
- For example:
- offset = 0x400160000
- end = 0x370
- map->m_la = 0x160370
- offset + end - map->m_la = 0x400000000
- offset + end - map->m_la = 0x00000000 (truncated as unsigned int)
- Expected result:
- cur = 0
- Actual result:
- cur = 0x370
Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
Fixes: 3883a79abd02 ("staging: erofs: introduce VLE decompression support")
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230710093410.44071-1-guochunhai@vivo.com
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/erofs/zdata.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index bf6a369f9c696..533e612b6a486 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -866,7 +866,7 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe,
*/
tight &= (fe->mode > Z_EROFS_PCLUSTER_FOLLOWED_NOINPLACE);
- cur = end - min_t(unsigned int, offset + end - map->m_la, end);
+ cur = end - min_t(erofs_off_t, offset + end - map->m_la, end);
if (!(map->m_flags & EROFS_MAP_MAPPED)) {
zero_user_segment(page, cur, end);
goto next_part;
--
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