[PATCH 2/v2] Fix "mount" MNT_CURSOR (kernels 5.8-6.7): Fix "mount" MNT_CURSOR entries (kernels 5.8-6.7): crash> mount > mount.out WARNING: cannot get super_block from vfsmnt: 0xff35d65eb1cc1820 crash> struct mount.mnt.mnt_sb,mnt.mnt_flags -x 0xff35d65eb1cc1820 mnt.mnt_sb = 0x0, mnt.mnt_flags = 0x10000000, When crashing with running "findmnt" commands, the mount list will have entries with mnt.mnt_flags==MNT_CURSOR (and mnt.mnt_sb==NULL). Such entries should be skipped without errors. Signed-off-by: Georges Aureau <georges.aureau(a)hpe.com&gt; -- defs.h | 2 ++ filesys.c | 15 +++++++++++++++ symbols.c | 4 ++++ 3 files changed, 21 insertions(+) diff --git a/defs.h b/defs.h index 156ac02..3fd7d89 100644 --- a/defs.h +++ b/defs.h @@ -2274,6 +2274,8 @@ struct offset_table { /* stash of commonly-used offsets */ long request_queue_tag_set; long blk_mq_tag_set_flags; long blk_mq_tag_set_shared_tags; + long vfsmount_mnt_flags; + long proc_mounts_cursor; }; struct size_table { /* stash of commonly-used sizes */ diff --git a/filesys.c b/filesys.c index 8d13807..1f8803d 100644 --- a/filesys.c +++ b/filesys.c @@ -1367,6 +1367,10 @@ cmd_mount(void) close_tmpfile(); } +/* For kernels 5.8-6.7, we're skipping show mount cursor entries. + */ +#define MNT_CURSOR 0x10000000 + /* * Do the work for cmd_mount(); */ @@ -1492,6 +1496,15 @@ show_mounts(ulong one_vfsmount, int flags, struct task_context *namespace_contex sbp = ULONG(vfsmount_buf + OFFSET(vfsmount_mnt_sb)); if (!IS_KVADDR(sbp)) { + if (sbp == 0 && VALID_MEMBER(proc_mounts_cursor) && + VALID_MEMBER(vfsmount_mnt_flags)) { + int mnt_flags = INT(vfsmount_buf + OFFSET(vfsmount_mnt_flags)); + if (mnt_flags == MNT_CURSOR) { + if (CRASHDEBUG(1)) + fprintf(stderr,"skipped cursor vfsmnt: 0x%lx\n", *vfsmnt); + continue; + } + } error(WARNING, "cannot get super_block from vfsmnt: 0x%lx\n", *vfsmnt); continue; } @@ -2081,6 +2094,8 @@ vfs_init(void) if (INVALID_MEMBER(vfsmount_mnt_devname)) MEMBER_OFFSET_INIT(mount_mnt_mountpoint, "mount", "mnt_mountpoint"); + MEMBER_OFFSET_INIT(vfsmount_mnt_flags, "vfsmount", "mnt_flags"); + MEMBER_OFFSET_INIT(proc_mounts_cursor, "proc_mounts", "cursor"); MEMBER_OFFSET_INIT(mount_mnt, "mount", "mnt"); MEMBER_OFFSET_INIT(namespace_root, "namespace", "root"); MEMBER_OFFSET_INIT(task_struct_nsproxy, "task_struct", "nsproxy"); diff --git a/symbols.c b/symbols.c index 112bcc6..fd91c2e 100644 --- a/symbols.c +++ b/symbols.c @@ -10691,6 +10691,10 @@ dump_offset_table(char *spec, ulong makestruct) OFFSET(vfsmount_mnt_mountpoint)); fprintf(fp, " vfsmount_mnt_parent: %ld\n", OFFSET(vfsmount_mnt_parent)); + fprintf(fp, " vfsmount_mnt_flags: %ld\n", + OFFSET(vfsmount_mnt_flags)); + fprintf(fp, " proc_mounts_cursor: %ld\n", + OFFSET(proc_mounts_cursor)); fprintf(fp, " mount_mnt_parent: %ld\n", OFFSET(mount_mnt_parent)); fprintf(fp, " mount_mnt_mountpoint: %ld\n",