6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: pangliyuan <pangliyuan1@xxxxxxxxxx> [ Upstream commit bdb0ca39e0acccf6771db49c3f94ed787d05f2d7 ] Clearing slab cache will free all znode in memory and make c->zroot.znode = NULL, then dumping tnc tree will access c->zroot.znode which cause null pointer dereference. Link: https://bugzilla.kernel.org/show_bug.cgi?id=219624#c0 Fixes: 1e51764a3c2a ("UBIFS: add new flash file system") Signed-off-by: pangliyuan <pangliyuan1@xxxxxxxxxx> Reviewed-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx> Signed-off-by: Richard Weinberger <richard@xxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/ubifs/debug.c | 22 +++++++++++++--------- 1 file changed, 13 insertions(+), 9 deletions(-) diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c index eef9e527d9ff9..ff9e574c07a87 100644 --- a/fs/ubifs/debug.c +++ b/fs/ubifs/debug.c @@ -946,16 +946,20 @@ void ubifs_dump_tnc(struct ubifs_info *c) pr_err("\n"); pr_err("(pid %d) start dumping TNC tree\n", current->pid); - znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, NULL); - level = znode->level; - pr_err("== Level %d ==\n", level); - while (znode) { - if (level != znode->level) { - level = znode->level; - pr_err("== Level %d ==\n", level); + if (c->zroot.znode) { + znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, NULL); + level = znode->level; + pr_err("== Level %d ==\n", level); + while (znode) { + if (level != znode->level) { + level = znode->level; + pr_err("== Level %d ==\n", level); + } + ubifs_dump_znode(c, znode); + znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, znode); } - ubifs_dump_znode(c, znode); - znode = ubifs_tnc_levelorder_next(c, c->zroot.znode, znode); + } else { + pr_err("empty TNC tree in memory\n"); } pr_err("(pid %d) finish dumping TNC tree\n", current->pid); } -- 2.39.5
