This reverts commit 89e0341af082dbc170019f908846f4a424efc86b.

In drivers/md/bcache/sysfs.c:bch_snprint_string_list(), NULL pointer at the end of list is necessary. Remove the NULL from last element of each lists will cause the following panic,

[ 4340.455652] bcache: register_cache() registered cache device nvme0n1 [ 4340.464603] bcache: register_bdev() registered backing device sdk [ 4421.587335] bcache: bch_cached_dev_run() cached dev sdk is running already [ 4421.587348] bcache: bch_cached_dev_attach() Caching sdk as bcache0 on set 354e1d46-d99f-4d8b-870b-078b80dc88a6 [ 5139.247950] general protection fault: 0000 [#1] SMP NOPTI [ 5139.247970] CPU: 9 PID: 5896 Comm: cat Not tainted 4.12.14-95.29-default #1 SLE12-SP4 [ 5139.247988] Hardware name: HPE ProLiant DL380 Gen10/ProLiant DL380 Gen10, BIOS U30 04/18/2019 [ 5139.248006] task: ffff888fb25c0b00 task.stack: ffff9bbacc704000 [ 5139.248021] RIP: 0010:string+0x21/0x70 [ 5139.248030] RSP: 0018:ffff9bbacc707bf0 EFLAGS: 00010286 [ 5139.248043] RAX: ffffffffa7e432e3 RBX: ffff8881c20da02a RCX: ffff0a00ffffff04 [ 5139.248058] RDX: 3f00656863616362 RSI: ffff8881c20db000 RDI: ffffffffffffffff [ 5139.248075] RBP: ffff8881c20db000 R08: 0000000000000000 R09: ffff8881c20da02a [ 5139.248090] R10: 0000000000000004 R11: 0000000000000000 R12: ffff9bbacc707c48 [ 5139.248104] R13: 0000000000000fd6 R14: ffffffffc0665855 R15: ffffffffc0665855 [ 5139.248119] FS: 00007faf253b8700(0000) GS:ffff88903f840000(0000) knlGS:0000000000000000 [ 5139.248137] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 5139.248149] CR2: 00007faf25395008 CR3: 0000000f72150006 CR4: 00000000007606e0 [ 5139.248164] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 5139.248179] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 5139.248193] PKRU: 55555554 [ 5139.248200] Call Trace: [ 5139.248210] vsnprintf+0x1fb/0x510 [ 5139.248221] snprintf+0x39/0x40 [ 5139.248238] bch_snprint_string_list.constprop.15+0x5b/0x90 [bcache] [ 5139.248256] __bch_cached_dev_show+0x44d/0x5f0 [bcache] [ 5139.248270] ? __alloc_pages_nodemask+0xb2/0x210 [ 5139.248284] bch_cached_dev_show+0x2c/0x50 [bcache] [ 5139.248297] sysfs_kf_seq_show+0xbb/0x190 [ 5139.248308] seq_read+0xfc/0x3c0 [ 5139.248317] __vfs_read+0x26/0x140 [ 5139.248327] vfs_read+0x87/0x130 [ 5139.248336] SyS_read+0x42/0x90 [ 5139.248346] do_syscall_64+0x74/0x160 [ 5139.248358] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 [ 5139.248370] RIP: 0033:0x7faf24eea370 [ 5139.248379] RSP: 002b:00007fff82d03f38 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 5139.248395] RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007faf24eea370 [ 5139.248411] RDX: 0000000000020000 RSI: 00007faf25396000 RDI: 0000000000000003 [ 5139.248426] RBP: 00007faf25396000 R08: 00000000ffffffff R09: 0000000000000000 [ 5139.248441] R10: 000000007c9d4d41 R11: 0000000000000246 R12: 00007faf25396000 [ 5139.248456] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000fff [ 5139.248892] Code: ff ff ff 0f 1f 80 00 00 00 00 49 89 f9 48 89 cf 48 c7 c0 e3 32 e4 a7 48 c1 ff 30 48 81 fa ff 0f 00 00 48 0f 46 d0 48 85 ff 74 45 <44> 0f b6 02 48 8d 42 01 45 84 c0 74 38 48 01 fa 4c 89 cf eb 0e

The simplest way to fix is to revert commit 89e0341af082 ("bcache: use sysfs_match_string() instead of __sysfs_match_string()").

This bug was introduced in Linux v5.2, so this fix only applies to Linux v5.2 is enough for stable tree maintainer.

Signed-off-by: Coly Li colyli@suse.de Reported-by: Peifeng Lin pflin@suse.com Cc: stable@vger.kernel.org Cc: Alexandru Ardelean alexandru.ardelean@analog.com --- drivers/md/bcache/sysfs.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/md/bcache/sysfs.c b/drivers/md/bcache/sysfs.c index 9f0826712845..e2059af90791 100644 --- a/drivers/md/bcache/sysfs.c +++ b/drivers/md/bcache/sysfs.c @@ -23,24 +23,28 @@ static const char * const bch_cache_modes[] = { "writethrough", "writeback", "writearound", - "none" + "none", + NULL };

/* Default is 0 ("auto") */ static const char * const bch_stop_on_failure_modes[] = { "auto", - "always" + "always", + NULL };

static const char * const cache_replacement_policies[] = { "lru", "fifo", - "random" + "random", + NULL };

static const char * const error_actions[] = { "unregister", - "panic" + "panic", + NULL };

write_attribute(attach); @@ -338,7 +342,7 @@ STORE(__cached_dev) }

if (attr == &sysfs_cache_mode) { - v = sysfs_match_string(bch_cache_modes, buf); + v = __sysfs_match_string(bch_cache_modes, -1, buf); if (v < 0) return v;

@@ -349,7 +353,7 @@ STORE(__cached_dev) }

if (attr == &sysfs_stop_when_cache_set_failed) { - v = sysfs_match_string(bch_stop_on_failure_modes, buf); + v = __sysfs_match_string(bch_stop_on_failure_modes, -1, buf); if (v < 0) return v;

@@ -816,7 +820,7 @@ STORE(__bch_cache_set) 0, UINT_MAX);

if (attr == &sysfs_errors) { - v = sysfs_match_string(error_actions, buf); + v = __sysfs_match_string(error_actions, -1, buf); if (v < 0) return v;

@@ -1088,7 +1092,7 @@ STORE(__bch_cache) }

if (attr == &sysfs_cache_replacement_policy) { - v = sysfs_match_string(cache_replacement_policies, buf); + v = __sysfs_match_string(cache_replacement_policies, -1, buf); if (v < 0) return v;