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FAILED: patch "[PATCH] ext4: fix leaking uninitialized memory in fast-commit journal" failed to apply to 5.10-stable tree

PATCH [email protected] 1 participant 1 message Jan 4, 2023

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The patch below does not apply to the 5.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

Possible dependencies:

594bc43b4103 ("ext4: fix leaking uninitialized memory in fast-commit journal") e9f53353e166 ("ext4: remove expensive flush on fast commit")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 594bc43b410316d70bb42aeff168837888d96810 Mon Sep 17 00:00:00 2001
From: Eric Biggers <[email protected]>
Date: Sun, 6 Nov 2022 14:48:37 -0800
Subject: [PATCH] ext4: fix leaking uninitialized memory in fast-commit journal

When space at the end of fast-commit journal blocks is unused, make sure to zero it out so that uninitialized memory is not leaked to disk.

Fixes aa75f4d3daae ("ext4: main fast-commit commit path")
Cc <[email protected]> # v5.10+
Signed-off-by Eric Biggers <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
Signed-off-by Theodore Ts'o <[email protected]>
fs/ext4/fast_commit.c +5 -0
index da0c8228cf9c..1e8be0554239 100644
@@ -737,6 +737,9 @@ static u8 *ext4_fc_reserve_space(struct super_block *sb, int len, u32 *crc)
 		*crc = ext4_chksum(sbi, *crc, tl, EXT4_FC_TAG_BASE_LEN);
 	if (pad_len > 0)
 		ext4_fc_memzero(sb, tl + 1, pad_len, crc);
+	/* Don't leak uninitialized memory in the unused last byte. */
+	*((u8 *)(tl + 1) + pad_len) = 0;
+
 	ext4_fc_submit_bh(sb, false);
 
 	ret = jbd2_fc_get_buf(EXT4_SB(sb)->s_journal, &bh);

@@ -793,6 +796,8 @@ static int ext4_fc_write_tail(struct super_block *sb, u32 crc)
 	dst += sizeof(tail.fc_tid);
 	tail.fc_crc = cpu_to_le32(crc);
 	ext4_fc_memcpy(sb, dst, &tail.fc_crc, sizeof(tail.fc_crc), NULL);
+	dst += sizeof(tail.fc_crc);
+	memset(dst, 0, bsize - off); /* Don't leak uninitialized memory. */
 
 	ext4_fc_submit_bh(sb, true);