On Thu, Apr 24, 2025 at 12:37:18AM +0800, I Hsin Cheng wrote: > Use "kvzalloc()" instead of "kvmalloc()" in btree_bounce_alloc() to > prevent uninit-value issue. > > Reported-by: syzbot+549710bad9c798e25...@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=549710bad9c798e25b15 > Fixes: cb6fc943b650 ("bcachefs: kill kvpmalloc()") > Signed-off-by: I Hsin Cheng <richard120...@gmail.com> > --- > syzbot reported an uninit-value issue. [1] > > Though the uninit value was detected in the context of crc32_body(), the > memory was actually allocated in "btree_bounce_alloc()". Use > "kvzalloc()" to allocate the memory can solve the issue, and I've tested > against syzbot. [2] > > If there're any further tests needed to be performed, please let me > know. I'll be more than happy to assist you with that, thanks !
See Documentation/filesystems/bcachefs/SubmittingPatches. And this isn't the correct fix - the correct fix is already in Linus's tree. > > [1]: > BUG: KMSAN: uninit-value in crc32_body lib/crc32.c:110 [inline] > BUG: KMSAN: uninit-value in crc32_le_generic lib/crc32.c:179 [inline] > BUG: KMSAN: uninit-value in __crc32c_le_base+0x43c/0xd80 lib/crc32.c:201 > crc32_body lib/crc32.c:110 [inline] > crc32_le_generic lib/crc32.c:179 [inline] > __crc32c_le_base+0x43c/0xd80 lib/crc32.c:201 > chksum_update+0x5b/0xd0 crypto/crc32c_generic.c:88 > crypto_shash_update+0x79/0xa0 crypto/shash.c:52 > crc32c+0xba/0x170 lib/libcrc32c.c:47 > bch2_checksum_update+0x106/0x1d0 fs/bcachefs/checksum.c:83 > bch2_checksum+0x3c5/0x7c0 fs/bcachefs/checksum.c:216 > __bch2_btree_node_write+0x528c/0x67c0 fs/bcachefs/btree_io.c:2151 > bch2_btree_node_write+0xa5/0x2e0 fs/bcachefs/btree_io.c:2288 > btree_node_write_if_need fs/bcachefs/btree_io.h:153 [inline] > __btree_node_flush+0x4d0/0x640 fs/bcachefs/btree_trans_commit.c:229 > bch2_btree_node_flush0+0x35/0x60 fs/bcachefs/btree_trans_commit.c:238 > journal_flush_pins+0xce6/0x1780 fs/bcachefs/journal_reclaim.c:553 > __bch2_journal_reclaim+0xd88/0x1610 fs/bcachefs/journal_reclaim.c:685 > bch2_journal_reclaim_thread+0x18e/0x760 fs/bcachefs/journal_reclaim.c:727 > kthread+0x3e2/0x540 kernel/kthread.c:389 > ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > Uninit was stored to memory at: > memcpy_u64s_small fs/bcachefs/util.h:511 [inline] > bkey_p_copy fs/bcachefs/bkey.h:46 [inline] > bch2_sort_keys+0x1b4d/0x2cb0 fs/bcachefs/bkey_sort.c:194 > __bch2_btree_node_write+0x3acd/0x67c0 fs/bcachefs/btree_io.c:2100 > bch2_btree_node_write+0xa5/0x2e0 fs/bcachefs/btree_io.c:2288 > btree_node_write_if_need fs/bcachefs/btree_io.h:153 [inline] > __btree_node_flush+0x4d0/0x640 fs/bcachefs/btree_trans_commit.c:229 > bch2_btree_node_flush0+0x35/0x60 fs/bcachefs/btree_trans_commit.c:238 > journal_flush_pins+0xce6/0x1780 fs/bcachefs/journal_reclaim.c:553 > __bch2_journal_reclaim+0xd88/0x1610 fs/bcachefs/journal_reclaim.c:685 > bch2_journal_reclaim_thread+0x18e/0x760 fs/bcachefs/journal_reclaim.c:727 > kthread+0x3e2/0x540 kernel/kthread.c:389 > ret_from_fork+0x6d/0x90 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > Uninit was created at: > __kmalloc_large_node+0x231/0x370 mm/slub.c:3994 > __do_kmalloc_node mm/slub.c:4027 [inline] > __kmalloc_node+0xb10/0x10c0 mm/slub.c:4046 > kmalloc_node include/linux/slab.h:648 [inline] > kvmalloc_node+0xc0/0x2d0 mm/util.c:634 > kvmalloc include/linux/slab.h:766 [inline] > btree_bounce_alloc fs/bcachefs/btree_io.c:118 [inline] > bch2_btree_node_read_done+0x4e68/0x75e0 fs/bcachefs/btree_io.c:1185 > btree_node_read_work+0x8a5/0x1eb0 fs/bcachefs/btree_io.c:1324 > bch2_btree_node_read+0x3d42/0x4b50 > __bch2_btree_root_read fs/bcachefs/btree_io.c:1748 [inline] > bch2_btree_root_read+0xa6c/0x13d0 fs/bcachefs/btree_io.c:1772 > read_btree_roots+0x454/0xee0 fs/bcachefs/recovery.c:457 > bch2_fs_recovery+0x7b6a/0x93e0 fs/bcachefs/recovery.c:785 > bch2_fs_start+0x7b2/0xbd0 fs/bcachefs/super.c:1043 > bch2_fs_open+0x152a/0x15f0 fs/bcachefs/super.c:2105 > bch2_mount+0x90d/0x1d90 fs/bcachefs/fs.c:1906 > legacy_get_tree+0x114/0x290 fs/fs_context.c:662 > vfs_get_tree+0xa7/0x570 fs/super.c:1779 > do_new_mount+0x71f/0x15e0 fs/namespace.c:3352 > path_mount+0x742/0x1f20 fs/namespace.c:3679 > do_mount fs/namespace.c:3692 [inline] > __do_sys_mount fs/namespace.c:3898 [inline] > __se_sys_mount+0x725/0x810 fs/namespace.c:3875 > __x64_sys_mount+0xe4/0x150 fs/namespace.c:3875 > x64_sys_call+0x2bf4/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:166 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > [2]: > https://lore.kernel.org/all/000000000000736bd40615100...@google.com/T/#m748384a36239a7f66e63cfde949e3db6bf14d5c6 > > syzbot reply me with: > Hello, > > syzbot has tested the proposed patch and the reproducer did not trigger any > issue: > > Reported-by: syzbot+549710bad9c798e25...@syzkaller.appspotmail.com > Tested-by: syzbot+549710bad9c798e25...@syzkaller.appspotmail.com > > Tested on: > > commit: 614da38e Merge tag 'hid-for-linus-2024051401' of git:/.. > git tree: > git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git > console output: https://syzkaller.appspot.com/x/log.txt?x=10be763f980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=49342144b6a907af > dashboard link: https://syzkaller.appspot.com/bug?extid=549710bad9c798e25b15 > compiler: Debian clang version 15.0.6, Debian LLD 15.0.6 > patch: https://syzkaller.appspot.com/x/patch.diff?x=15b99a6f980000 > > Note: testing is done by a robot and is best-effort only. > > Best regards, > I Hsin Cheng > --- > fs/bcachefs/btree_io.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/bcachefs/btree_io.c b/fs/bcachefs/btree_io.c > index debb0edc3455..dc00c5273ffe 100644 > --- a/fs/bcachefs/btree_io.c > +++ b/fs/bcachefs/btree_io.c > @@ -115,7 +115,7 @@ static void *btree_bounce_alloc(struct bch_fs *c, size_t > size, > BUG_ON(size > c->opts.btree_node_size); > > *used_mempool = false; > - p = kvmalloc(size, __GFP_NOWARN|GFP_NOWAIT); > + p = kvzalloc(size, __GFP_NOWARN|GFP_NOWAIT); > if (!p) { > *used_mempool = true; > p = mempool_alloc(&c->btree_bounce_pool, GFP_NOFS); > -- > 2.43.0 >
