mainline inclusion from mainline-v6.8-rc1 commit c07a4dab243a99589bdfd5ec364b5cb1db6b70f3 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9VPBQ CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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The checking of @c->nroot->flags and @c->dirty_[n|p]n_cnt in function nothing_to_commit() is not atomic, which could be raced with modifying of lpt, for example: P1 P2 P3 run_gc ubifs_garbage_collect do_commit ubifs_return_leb ubifs_lpt_lookup_dirty dirty_cow_nnode do_commit nothing_to_commit if (test_bit(DIRTY_CNODE, &c->nroot->flags) // false test_and_set_bit(DIRTY_CNODE, &nnode->flags) c->dirty_nn_cnt += 1 ubifs_assert(c, c->dirty_nn_cnt == 0) // false !
Fetch a reproducer in Link: UBIFS error (ubi0:0 pid 2747): ubifs_assert_failed UBIFS assert failed: c->dirty_pn_cnt == 0, in fs/ubifs/commit.c Call Trace: ubifs_ro_mode+0x58/0x70 [ubifs] ubifs_assert_failed+0x6a/0x90 [ubifs] do_commit+0x5b7/0x930 [ubifs] ubifs_run_commit+0xc6/0x1a0 [ubifs] ubifs_sync_fs+0xd8/0x110 [ubifs] sync_filesystem+0xb4/0x120 do_syscall_64+0x6f/0x140
Fix it by checking @c->dirty_[n|p]n_cnt and @c->nroot state with @c->lp_mutex locked.
Fixes: 944fdef52ca9 ("UBIFS: do not start the commit if there is nothing to commit") Link: https://bugzilla.kernel.org/show_bug.cgi?id=218162 Signed-off-by: Zhihao Cheng chengzhihao1@huawei.com Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Zhihao Cheng chengzhihao@huaweicloud.com --- fs/ubifs/commit.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/fs/ubifs/commit.c b/fs/ubifs/commit.c index c4fc1047fc07..5b3a840098b0 100644 --- a/fs/ubifs/commit.c +++ b/fs/ubifs/commit.c @@ -69,6 +69,14 @@ static int nothing_to_commit(struct ubifs_info *c) if (c->zroot.znode && ubifs_zn_dirty(c->zroot.znode)) return 0;
+ /* + * Increasing @c->dirty_pn_cnt/@c->dirty_nn_cnt and marking + * nnodes/pnodes as dirty in run_gc() could race with following + * checking, which leads inconsistent states between @c->nroot + * and @c->dirty_pn_cnt/@c->dirty_nn_cnt, holding @c->lp_mutex + * to avoid that. + */ + mutex_lock(&c->lp_mutex); /* * Even though the TNC is clean, the LPT tree may have dirty nodes. For * example, this may happen if the budgeting subsystem invoked GC to @@ -76,12 +84,15 @@ static int nothing_to_commit(struct ubifs_info *c) * free space. In this case GC would just change the lprops of this * LEB (by turning all space into free space) and unmap it. */ - if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags)) + if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags)) { + mutex_unlock(&c->lp_mutex); return 0; + }
ubifs_assert(c, atomic_long_read(&c->dirty_zn_cnt) == 0); ubifs_assert(c, c->dirty_pn_cnt == 0); ubifs_assert(c, c->dirty_nn_cnt == 0); + mutex_unlock(&c->lp_mutex);
return 1; }