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| author |   Eric Biggers <ebiggers@google.com> | 2019-10-16 19:48:14 -0700 |
|---|---|---|
| committer |   Al Viro <viro@zeniv.linux.org.uk> | 2019-10-16 23:15:09 -0400 |
| commit | 0ecee66990644c3482209ff7c12faa7bc40449b1 (patch) | |
| tree | b851ba3d0c8801481a22c73182ef338faef632d5 /fs/namespace.c | |
| parent | Linux 5.4-rc3 (diff) | |
| download | linux-dev-0ecee66990644c3482209ff7c12faa7bc40449b1.tar.xz linux-dev-0ecee66990644c3482209ff7c12faa7bc40449b1.zip | |
fs/namespace.c: fix use-after-free of mount in mnt_warn_timestamp_expiry()
After do_add_mount() returns success, the caller doesn't hold a
reference to the 'struct mount' anymore. So it's invalid to access it
in mnt_warn_timestamp_expiry().
Fix it by calling mnt_warn_timestamp_expiry() before do_add_mount()
rather than after, and adjusting the warning message accordingly.
Reported-by: syzbot+da4f525235510683d855@syzkaller.appspotmail.com
Fixes: f8b92ba67c5d ("mount: Add mount warning for impending timestamp expiry")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index fe0e9e1410fe..2adfe7b166a3 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -2478,8 +2478,10 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount * time64_to_tm(sb->s_time_max, 0, &tm); - pr_warn("Mounted %s file system at %s supports timestamps until %04ld (0x%llx)\n", - sb->s_type->name, mntpath, + pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n", + sb->s_type->name, + is_mounted(mnt) ? "remounted" : "mounted", + mntpath, tm.tm_year+1900, (unsigned long long)sb->s_time_max); free_page((unsigned long)buf); @@ -2764,14 +2766,11 @@ static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, if (IS_ERR(mnt)) return PTR_ERR(mnt); - error = do_add_mount(real_mount(mnt), mountpoint, mnt_flags); - if (error < 0) { - mntput(mnt); - return error; - } - mnt_warn_timestamp_expiry(mountpoint, mnt); + error = do_add_mount(real_mount(mnt), mountpoint, mnt_flags); + if (error < 0) + mntput(mnt); return error; } |