From: Zhihao Cheng chengzhihao1@huawei.com
[ Upstream commit 6abf57262166b4f4294667fb5206ae7ba1ba96f5 ]
Running stress-test test_2 in mtd-utils on ubi device, sometimes we can get following oops message:
BUG: unable to handle page fault for address: ffffffff00000140 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 280a067 P4D 280a067 PUD 0 Oops: 0000 [#1] SMP CPU: 0 PID: 60 Comm: kworker/u16:1 Kdump: loaded Not tainted 5.2.0 #13 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0 -0-ga698c8995f-prebuilt.qemu.org 04/01/2014 Workqueue: writeback wb_workfn (flush-ubifs_0_0) RIP: 0010:rb_next_postorder+0x2e/0xb0 Code: 80 db 03 01 48 85 ff 0f 84 97 00 00 00 48 8b 17 48 83 05 bc 80 db 03 01 48 83 e2 fc 0f 84 82 00 00 00 48 83 05 b2 80 db 03 01 <48> 3b 7a 10 48 89 d0 74 02 f3 c3 48 8b 52 08 48 83 05 a3 80 db 03 RSP: 0018:ffffc90000887758 EFLAGS: 00010202 RAX: ffff888129ae4700 RBX: ffff888138b08400 RCX: 0000000080800001 RDX: ffffffff00000130 RSI: 0000000080800024 RDI: ffff888138b08400 RBP: ffff888138b08400 R08: ffffea0004a6b920 R09: 0000000000000000 R10: ffffc90000887740 R11: 0000000000000001 R12: ffff888128d48000 R13: 0000000000000800 R14: 000000000000011e R15: 00000000000007c8 FS: 0000000000000000(0000) GS:ffff88813ba00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffff00000140 CR3: 000000013789d000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: destroy_old_idx+0x5d/0xa0 [ubifs] ubifs_tnc_start_commit+0x4fe/0x1380 [ubifs] do_commit+0x3eb/0x830 [ubifs] ubifs_run_commit+0xdc/0x1c0 [ubifs]
Above Oops are due to the slab-out-of-bounds happened in do-while of function layout_in_gaps indirectly called by ubifs_tnc_start_commit. In function layout_in_gaps, there is a do-while loop placing index nodes into the gaps created by obsolete index nodes in non-empty index LEBs until rest index nodes can totally be placed into pre-allocated empty LEBs. @c->gap_lebs points to a memory area(integer array) which records LEB numbers used by 'in-the-gaps' method. Whenever a fitable index LEB is found, corresponding lnum will be incrementally written into the memory area pointed by @c->gap_lebs. The size ((@c->lst.idx_lebs + 1) * sizeof(int)) of memory area is allocated before do-while loop and can not be changed in the loop. But @c->lst.idx_lebs could be increased by function ubifs_change_lp (called by layout_leb_in_gaps->ubifs_find_dirty_idx_leb->get_idx_gc_leb) during the loop. So, sometimes oob happens when number of cycles in do-while loop exceeds the original value of @c->lst.idx_lebs. See detail in https://bugzilla.kernel.org/show_bug.cgi?id=204229. This patch fixes oob in layout_in_gaps.
Signed-off-by: Zhihao Cheng chengzhihao1@huawei.com Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Sasha Levin sashal@kernel.org --- fs/ubifs/tnc_commit.c | 34 +++++++++++++++++++++++++++------- 1 file changed, 27 insertions(+), 7 deletions(-)
diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c index a384a0f9ff32..234be1c4dc87 100644 --- a/fs/ubifs/tnc_commit.c +++ b/fs/ubifs/tnc_commit.c @@ -212,7 +212,7 @@ static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key, /** * layout_leb_in_gaps - layout index nodes using in-the-gaps method. * @c: UBIFS file-system description object - * @p: return LEB number here + * @p: return LEB number in @c->gap_lebs[p] * * This function lays out new index nodes for dirty znodes using in-the-gaps * method of TNC commit. @@ -221,7 +221,7 @@ static int is_idx_node_in_use(struct ubifs_info *c, union ubifs_key *key, * This function returns the number of index nodes written into the gaps, or a * negative error code on failure. */ -static int layout_leb_in_gaps(struct ubifs_info *c, int *p) +static int layout_leb_in_gaps(struct ubifs_info *c, int p) { struct ubifs_scan_leb *sleb; struct ubifs_scan_node *snod; @@ -236,7 +236,7 @@ static int layout_leb_in_gaps(struct ubifs_info *c, int *p) * filled, however we do not check there at present. */ return lnum; /* Error code */ - *p = lnum; + c->gap_lebs[p] = lnum; dbg_gc("LEB %d", lnum); /* * Scan the index LEB. We use the generic scan for this even though @@ -355,7 +355,7 @@ static int get_leb_cnt(struct ubifs_info *c, int cnt) */ static int layout_in_gaps(struct ubifs_info *c, int cnt) { - int err, leb_needed_cnt, written, *p; + int err, leb_needed_cnt, written, p = 0, old_idx_lebs, *gap_lebs;
dbg_gc("%d znodes to write", cnt);
@@ -364,9 +364,9 @@ static int layout_in_gaps(struct ubifs_info *c, int cnt) if (!c->gap_lebs) return -ENOMEM;
- p = c->gap_lebs; + old_idx_lebs = c->lst.idx_lebs; do { - ubifs_assert(c, p < c->gap_lebs + c->lst.idx_lebs); + ubifs_assert(c, p < c->lst.idx_lebs); written = layout_leb_in_gaps(c, p); if (written < 0) { err = written; @@ -392,9 +392,29 @@ static int layout_in_gaps(struct ubifs_info *c, int cnt) leb_needed_cnt = get_leb_cnt(c, cnt); dbg_gc("%d znodes remaining, need %d LEBs, have %d", cnt, leb_needed_cnt, c->ileb_cnt); + /* + * Dynamically change the size of @c->gap_lebs to prevent + * oob, because @c->lst.idx_lebs could be increased by + * function @get_idx_gc_leb (called by layout_leb_in_gaps-> + * ubifs_find_dirty_idx_leb) during loop. Only enlarge + * @c->gap_lebs when needed. + * + */ + if (leb_needed_cnt > c->ileb_cnt && p >= old_idx_lebs && + old_idx_lebs < c->lst.idx_lebs) { + old_idx_lebs = c->lst.idx_lebs; + gap_lebs = krealloc(c->gap_lebs, sizeof(int) * + (old_idx_lebs + 1), GFP_NOFS); + if (!gap_lebs) { + kfree(c->gap_lebs); + c->gap_lebs = NULL; + return -ENOMEM; + } + c->gap_lebs = gap_lebs; + } } while (leb_needed_cnt > c->ileb_cnt);
- *p = -1; + c->gap_lebs[p] = -1; return 0; }