From: Sasha Levin Date: Fri, 25 Oct 2019 01:34:05 +0000 (-0400) Subject: fixes for 4.19 X-Git-Tag: v4.4.198~47^2~3 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=77ebb356c420712719634255d2d3e26fa50ecf3e;p=thirdparty%2Fkernel%2Fstable-queue.git fixes for 4.19 Signed-off-by: Sasha Levin --- diff --git a/queue-4.19/mm-memfd-should-be-lock-the-radix_tree-when-iteratin.patch b/queue-4.19/mm-memfd-should-be-lock-the-radix_tree-when-iteratin.patch new file mode 100644 index 00000000000..f6250f7ab60 --- /dev/null +++ b/queue-4.19/mm-memfd-should-be-lock-the-radix_tree-when-iteratin.patch @@ -0,0 +1,95 @@ +From f4096b3c428fb472ade1b6c65952ea7a7866f9d7 Mon Sep 17 00:00:00 2001 +From: Sasha Levin +Date: Thu, 24 Oct 2019 23:03:20 +0800 +Subject: mm/memfd: should be lock the radix_tree when iterating its slot + +From: zhong jiang + +Recently, We test an linux 4.19 stable and find the following issue. + +kernel BUG at lib/radix-tree.c:1429! +invalid opcode: 0000 [#1] SMP KASAN PTI +CPU: 7 PID: 6935 Comm: syz-executor.2 Not tainted 4.19.36 #25 +Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 +RIP: 0010:radix_tree_tag_set+0x200/0x2f0 lib/radix-tree.c:1429 +Code: 00 00 5b 5d 41 5c 41 5d 41 5e 41 5f c3 48 89 44 24 10 e8 a3 29 7e fe 48 8b 44 24 10 48 0f ab 03 e9 d2 fe ff ff e8 90 29 7e fe <0f> 0b 48 c7 c7 e0 5a 87 84 e8 f0 e7 08 ff 4c 89 ef e8 4a ff ac fe +RSP: 0018:ffff88837b13fb60 EFLAGS: 00010016 +RAX: 0000000000040000 RBX: ffff8883c5515d58 RCX: ffffffff82cb2ef0 +RDX: 0000000000000b72 RSI: ffffc90004cf2000 RDI: ffff8883c5515d98 +RBP: ffff88837b13fb98 R08: ffffed106f627f7e R09: ffffed106f627f7e +R10: 0000000000000001 R11: ffffed106f627f7d R12: 0000000000000004 +R13: ffffea000d7fea80 R14: 1ffff1106f627f6f R15: 0000000000000002 +FS: 00007fa1b8df2700(0000) GS:ffff8883e2fc0000(0000) knlGS:0000000000000000 +CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 +CR2: 00007fa1b8df1db8 CR3: 000000037d4d2001 CR4: 0000000000160ee0 +Call Trace: + memfd_tag_pins mm/memfd.c:51 [inline] + memfd_wait_for_pins+0x2c5/0x12d0 mm/memfd.c:81 + memfd_add_seals mm/memfd.c:215 [inline] + memfd_fcntl+0x33d/0x4a0 mm/memfd.c:247 + do_fcntl+0x589/0xeb0 fs/fcntl.c:421 + __do_sys_fcntl fs/fcntl.c:463 [inline] + __se_sys_fcntl fs/fcntl.c:448 [inline] + __x64_sys_fcntl+0x12d/0x180 fs/fcntl.c:448 + do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:293 + +By reviewing the code, I find that there is an race between iterate +the radix_tree and radix_tree_insert/delete. Because the former just +access its slot in rcu protected period. but it fails to prevent the +radix_tree from being changed. + +On Thu, Oct 24, 2019 at 10:41:15AM -0700, Matthew Wilcox wrote: +>The locking here now matches the locking in memfd_tag_pins() that +>was changed in ef3038a573aa8bf2f3797b110f7244b55a0e519c (part of 4.20-rc1). +>I didn't notice that I was fixing a bug when I changed the locking. +>This bug has been present since 05f65b5c70909ef686f865f0a85406d74d75f70f +>(part of 3.17) so backports will need to go further back. This code has +>moved around a bit (mm/shmem.c) and the APIs have changed, so it will +>take some effort + +Cc: stable@vger.kernel.org +Signed-off-by: zhong jiang +Reviewed-by: Matthew Wilcox (Oracle) +Signed-off-by: Sasha Levin +--- + mm/memfd.c | 8 +++----- + 1 file changed, 3 insertions(+), 5 deletions(-) + +diff --git a/mm/memfd.c b/mm/memfd.c +index 2bb5e257080e9..0b3fedc779236 100644 +--- a/mm/memfd.c ++++ b/mm/memfd.c +@@ -37,8 +37,8 @@ static void memfd_tag_pins(struct address_space *mapping) + + lru_add_drain(); + start = 0; +- rcu_read_lock(); + ++ xa_lock_irq(&mapping->i_pages); + radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) { + page = radix_tree_deref_slot(slot); + if (!page || radix_tree_exception(page)) { +@@ -47,18 +47,16 @@ static void memfd_tag_pins(struct address_space *mapping) + continue; + } + } else if (page_count(page) - page_mapcount(page) > 1) { +- xa_lock_irq(&mapping->i_pages); + radix_tree_tag_set(&mapping->i_pages, iter.index, + MEMFD_TAG_PINNED); +- xa_unlock_irq(&mapping->i_pages); + } + + if (need_resched()) { + slot = radix_tree_iter_resume(slot, &iter); +- cond_resched_rcu(); ++ cond_resched_lock(&mapping->i_pages.xa_lock); + } + } +- rcu_read_unlock(); ++ xa_unlock_irq(&mapping->i_pages); + } + + /* +-- +2.20.1 + diff --git a/queue-4.19/series b/queue-4.19/series index 5fedf6d51b1..6c471cad417 100644 --- a/queue-4.19/series +++ b/queue-4.19/series @@ -22,3 +22,4 @@ libata-ahci-fix-pcs-quirk-application.patch md-raid0-fix-warning-message-for-parameter-default_l.patch revert-drm-radeon-fix-eeh-during-kexec.patch ocfs2-fix-panic-due-to-ocfs2_wq-is-null.patch +mm-memfd-should-be-lock-the-radix_tree-when-iteratin.patch