linux-kernel - [PATCH] jffs2: fix use of uninitialized variable

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Date: Mon,  1 Jul 2024 12:52:05 +0800
From: Qingfang Deng <dqfext@...il.com>
To: David Woodhouse <dwmw2@...radead.org>,
	Richard Weinberger <richard@....at>,
	Qingfang Deng <qingfang.deng@...lower.com.cn>,
	linux-mtd@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] jffs2: fix use of uninitialized variable

From: Qingfang Deng <qingfang.deng@...lower.com.cn>

When building the kernel with -Wmaybe-uninitialized, the compiler
reports this warning:

In function 'jffs2_mark_erased_block',
    inlined from 'jffs2_erase_pending_blocks' at fs/jffs2/erase.c:116:4:
fs/jffs2/erase.c:474:9: warning: 'bad_offset' may be used uninitialized [-Wmaybe-uninitialized]
  474 |         jffs2_erase_failed(c, jeb, bad_offset);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
fs/jffs2/erase.c: In function 'jffs2_erase_pending_blocks':
fs/jffs2/erase.c:402:18: note: 'bad_offset' was declared here
  402 |         uint32_t bad_offset;
      |                  ^~~~~~~~~~

When mtd->point() is used, jffs2_erase_pending_blocks can return -EIO
without initializing bad_offset, which is later used at the filebad
label in jffs2_mark_erased_block.
Fix it by initializing this variable.

Fixes: 8a0f572397ca ("[JFFS2] Return values of jffs2_block_check_erase error paths")
Signed-off-by: Qingfang Deng <qingfang.deng@...lower.com.cn>
---
 fs/jffs2/erase.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/fs/jffs2/erase.c b/fs/jffs2/erase.c
index acd32f05b519..ef3a1e1b6cb0 100644
--- a/fs/jffs2/erase.c
+++ b/fs/jffs2/erase.c
@@ -338,10 +338,9 @@ static int jffs2_block_check_erase(struct jffs2_sb_info *c, struct jffs2_erasebl
 		} while(--retlen);
 		mtd_unpoint(c->mtd, jeb->offset, c->sector_size);
 		if (retlen) {
-			pr_warn("Newly-erased block contained word 0x%lx at offset 0x%08tx\n",
-				*wordebuf,
-				jeb->offset +
-				c->sector_size-retlen * sizeof(*wordebuf));
+			*bad_offset = jeb->offset + c->sector_size - retlen * sizeof(*wordebuf);
+			pr_warn("Newly-erased block contained word 0x%lx at offset 0x%08x\n",
+				*wordebuf, *bad_offset);
 			return -EIO;
 		}
 		return 0;
-- 
2.34.1