linux-ext4 - [PATCH v2 4/4] e2fsck: initialize variable before first use in fast commit replay

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Date:   Tue, 23 Feb 2021 09:41:56 -0800
From:   Harshad Shirwadkar <harshadshirwadkar@...il.com>
To:     linux-ext4@...r.kernel.org
Cc:     tytso@....edu, Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: [PATCH v2 4/4] e2fsck: initialize variable before first use in fast commit replay

From: Harshad Shirwadkar <harshadshirwadkar@...il.com>

Initialize ext2fs_ex variable in ext4_fc_replay_scan() before first
use. Also ensure make ext2fs_decode_extent completely overwrite the
extent structure passed to it as argument to prevent potential future
bugs for the users of the function.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
---
 e2fsck/journal.c    | 2 +-
 lib/ext2fs/extent.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/e2fsck/journal.c b/e2fsck/journal.c
index a67ef745..8e7ba819 100644
--- a/e2fsck/journal.c
+++ b/e2fsck/journal.c
@@ -289,7 +289,7 @@ static int ext4_fc_replay_scan(journal_t *j, struct buffer_head *bh,
 	struct ext4_fc_tail *tail;
 	__u8 *start, *end;
 	struct ext4_fc_head *head;
-	struct ext2fs_extent ext2fs_ex;
+	struct ext2fs_extent ext2fs_ex = {0};
 
 	state = &ctx->fc_replay_state;
 
diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
index 9e611038..b324c7b0 100644
--- a/lib/ext2fs/extent.c
+++ b/lib/ext2fs/extent.c
@@ -1797,7 +1797,7 @@ errcode_t ext2fs_decode_extent(struct ext2fs_extent *to, void *addr, int len)
 			<< 32);
 	to->e_lblk = ext2fs_le32_to_cpu(from->ee_block);
 	to->e_len = ext2fs_le16_to_cpu(from->ee_len);
-	to->e_flags |= EXT2_EXTENT_FLAGS_LEAF;
+	to->e_flags = EXT2_EXTENT_FLAGS_LEAF;
 	if (to->e_len > EXT_INIT_MAX_LEN) {
 		to->e_len -= EXT_INIT_MAX_LEN;
 		to->e_flags |= EXT2_EXTENT_FLAGS_UNINIT;
-- 
2.30.0.617.g56c4b15f3c-goog