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Commit ca0d1707 authored by Andreas Dilger's avatar Andreas Dilger Committed by Greg Kroah-Hartman
Browse files

ext4: don't assume that mmp_nodename/bdevname have NUL 

commit 14c9ca0583eee8df285d68a0e6ec71053efd2228 upstream.

Don't assume that the mmp_nodename and mmp_bdevname strings are NUL
terminated, since they are filled in by snprintf(), which is not
guaranteed to do so.

Link: https://lore.kernel.org/r/1580076215-1048-1-git-send-email-adilger@dilger.ca


Signed-off-by: default avatarAndreas Dilger <adilger@dilger.ca>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8e57f6a6

fs/ext4/mmp.c

+7 −5
Original line number Diff line number Diff line
@@ -120,10 +120,10 @@ void __dump_mmp_msg(struct super_block *sb, struct mmp_struct *mmp, 
{

	__ext4_warning(sb, function, line, "%s", msg);

	__ext4_warning(sb, function, line,

		       "MMP failure info: last update time: %llu, last update "

		       "node: %s, last update device: %s",

		       (long long unsigned int) le64_to_cpu(mmp->mmp_time),

		       mmp->mmp_nodename, mmp->mmp_bdevname);

		       "MMP failure info: last update time: %llu, last update node: %.*s, last update device: %.*s",

		       (unsigned long long)le64_to_cpu(mmp->mmp_time),

		       (int)sizeof(mmp->mmp_nodename), mmp->mmp_nodename,

		       (int)sizeof(mmp->mmp_bdevname), mmp->mmp_bdevname);

}



/*
@@ -154,6 +154,7 @@ static int kmmpd(void *data) 
	mmp_check_interval = max(EXT4_MMP_CHECK_MULT * mmp_update_interval,

				 EXT4_MMP_MIN_CHECK_INTERVAL);

	mmp->mmp_check_interval = cpu_to_le16(mmp_check_interval);

	BUILD_BUG_ON(sizeof(mmp->mmp_bdevname) < BDEVNAME_SIZE);

	bdevname(bh->b_bdev, mmp->mmp_bdevname);



	memcpy(mmp->mmp_nodename, init_utsname()->nodename,
@@ -375,7 +376,8 @@ int ext4_multi_mount_protect(struct super_block *sb, 
	/*

	 * Start a kernel thread to update the MMP block periodically.

	 */

	EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%s",

	EXT4_SB(sb)->s_mmp_tsk = kthread_run(kmmpd, mmpd_data, "kmmpd-%.*s",

					     (int)sizeof(mmp->mmp_bdevname),

					     bdevname(bh->b_bdev,

						      mmp->mmp_bdevname));

	if (IS_ERR(EXT4_SB(sb)->s_mmp_tsk)) {