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Date: Tue, 14 Jan 2020 14:42:17 -0700
From: Andreas Dilger <adilger@...ger.ca>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org, Andreas Dilger <adilger@...ger.ca>
Subject: [PATCH 1/2] mmp: don't assume NUL termination for MMP strings
Don't assume that mmp_nodename and mmp_bdevname are NUL terminated,
since very long node/device names may completely fill the buffers.
Limit string printing to the maximum buffer size for safety, and
change the field definitions to __u8 to make it more clear that
they are not NUL-terminated strings, as is done with other strings
in the superblock that do not have NUL termination.
Signed-off-by: Andreas Dilger <adilger@...ger.ca>
---
debugfs/debugfs.c | 6 ++++--
e2fsck/util.c | 8 ++++++--
lib/ext2fs/ext2_fs.h | 6 +++---
misc/dumpe2fs.c | 14 ++++++++++----
misc/util.c | 7 +++++--
tests/filter.sed | 1 +
6 files changed, 29 insertions(+), 13 deletions(-)
diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index 9b70145..7cfc269 100644
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -2446,8 +2446,10 @@ void do_dump_mmp(int argc EXT2FS_ATTR((unused)), char *argv[],
fprintf(stdout, "check_interval: %d\n", mmp_s->mmp_check_interval);
fprintf(stdout, "sequence: %08x\n", mmp_s->mmp_seq);
fprintf(stdout, "time: %lld -- %s", mmp_s->mmp_time, ctime(&t));
- fprintf(stdout, "node_name: %s\n", mmp_s->mmp_nodename);
- fprintf(stdout, "device_name: %s\n", mmp_s->mmp_bdevname);
+ fprintf(stdout, "node_name: %.*s\n",
+ (int)sizeof(mmp_s->mmp_nodename), (char *)mmp_s->mmp_nodename);
+ fprintf(stdout, "device_name: %.*s\n",
+ (int)sizeof(mmp_s->mmp_bdevname), (char *)mmp_s->mmp_bdevname);
fprintf(stdout, "magic: 0x%x\n", mmp_s->mmp_magic);
fprintf(stdout, "checksum: 0x%08x\n", mmp_s->mmp_checksum);
}
diff --git a/e2fsck/util.c b/e2fsck/util.c
index db6a1cc..07885ab 100644
--- a/e2fsck/util.c
+++ b/e2fsck/util.c
@@ -777,8 +777,12 @@ void dump_mmp_msg(struct mmp_struct *mmp, const char *fmt, ...)
printf(" mmp_sequence: %08x\n", mmp->mmp_seq);
printf(" mmp_update_date: %s", ctime(&t));
printf(" mmp_update_time: %lld\n", mmp->mmp_time);
- printf(" mmp_node_name: %s\n", mmp->mmp_nodename);
- printf(" mmp_device_name: %s\n", mmp->mmp_bdevname);
+ printf(" mmp_node_name: %.*s\n",
+ (int)sizeof(mmp->mmp_nodename),
+ (char *)mmp->mmp_nodename);
+ printf(" mmp_device_name: %.*s\n",
+ (int)sizeof(mmp->mmp_bdevname),
+ (char *)mmp->mmp_bdevname);
}
}
diff --git a/lib/ext2fs/ext2_fs.h b/lib/ext2fs/ext2_fs.h
index 3165b38..79816b6 100644
--- a/lib/ext2fs/ext2_fs.h
+++ b/lib/ext2fs/ext2_fs.h
@@ -1098,9 +1098,9 @@ struct ext2_dir_entry_tail {
struct mmp_struct {
__u32 mmp_magic; /* Magic number for MMP */
__u32 mmp_seq; /* Sequence no. updated periodically */
- __u64 mmp_time; /* Time last updated */
- char mmp_nodename[64]; /* Node which last updated MMP block */
- char mmp_bdevname[32]; /* Bdev which last updated MMP block */
+ __u64 mmp_time; /* Time last updated (seconds) */
+ __u8 mmp_nodename[64]; /* Node updating MMP block, no NUL? */
+ __u8 mmp_bdevname[32]; /* Bdev updating MMP block, no NUL? */
__u16 mmp_check_interval; /* Changed mmp_check_interval */
__u16 mmp_pad1;
__u32 mmp_pad2[226];
diff --git a/misc/dumpe2fs.c b/misc/dumpe2fs.c
index 9a6f586..a6053d2 100644
--- a/misc/dumpe2fs.c
+++ b/misc/dumpe2fs.c
@@ -439,8 +439,12 @@ static int check_mmp(ext2_filsys fs)
time_t mmp_time = mmp->mmp_time;
fprintf(stderr,
- "%s: MMP last updated by '%s' on %s",
- program_name, mmp->mmp_nodename,
+ "%s: MMP update by '%.*s%.*s' at %s",
+ program_name,
+ (int)sizeof(mmp->mmp_nodename),
+ (char *)mmp->mmp_nodename,
+ (int)sizeof(mmp->mmp_bdevname),
+ (char *)mmp->mmp_bdevname,
ctime(&mmp_time));
}
retval = 1;
@@ -489,8 +493,10 @@ static void print_mmp_block(ext2_filsys fs)
printf(" mmp_sequence: %#08x\n", mmp->mmp_seq);
printf(" mmp_update_date: %s", ctime(&mmp_time));
printf(" mmp_update_time: %lld\n", mmp->mmp_time);
- printf(" mmp_node_name: %s\n", mmp->mmp_nodename);
- printf(" mmp_device_name: %s\n", mmp->mmp_bdevname);
+ printf(" mmp_node_name: %.*s\n",
+ (int)sizeof(mmp->mmp_nodename), (char *)mmp->mmp_nodename);
+ printf(" mmp_device_name: %.*s\n",
+ (int)sizeof(mmp->mmp_bdevname), (char *)mmp->mmp_bdevname);
}
static void parse_extended_opts(const char *opts, blk64_t *superblock,
diff --git a/misc/util.c b/misc/util.c
index 7799158..6239b36 100644
--- a/misc/util.c
+++ b/misc/util.c
@@ -288,7 +288,10 @@ void dump_mmp_msg(struct mmp_struct *mmp, const char *msg)
if (mmp) {
time_t t = mmp->mmp_time;
- printf("MMP error info: last update: %s node: %s device: %s\n",
- ctime(&t), mmp->mmp_nodename, mmp->mmp_bdevname);
+ printf("MMP error info: node: %.*s, device: %.*s, updated: %s",
+ (int)sizeof(mmp->mmp_nodename),
+ (char *)mmp->mmp_nodename,
+ (int)sizeof(mmp->mmp_bdevname),
+ (char *)mmp->mmp_bdevname, ctime(&t));
}
}
diff --git a/tests/filter.sed b/tests/filter.sed
index f37986c..796186e 100644
--- a/tests/filter.sed
+++ b/tests/filter.sed
@@ -37,3 +37,4 @@ s/mmp_node_name: .*/mmp_node_name: test_node/
s/mmp_update_date: .*/mmp_update_date: test date/
s/mmp_update_time: .*/mmp_update_time: test_time/
s/MMP last updated by '.*' on .*/MMP last updated by 'test_node' on test date/
+s/MMP update by '.*' at .*/MMP last updated by 'test_node' on test date/
--
1.8.0
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