From: Bart Van Assche bvanassche@acm.org
[ Upstream commit b9853b4d6fb403ccb1d4d82e2d39fc17fc07519c ]
Although it is not clear to me why UBSAN complains when 'memory_backed' is set, this patch suppresses the UBSAN complaint that is triggered when setting that configfs attribute.
UBSAN: Undefined behaviour in drivers/block/null_blk_main.c:327:1 load of value 16 is not a valid value for type '_Bool' CPU: 2 PID: 8396 Comm: check Not tainted 5.6.0-rc1-dbg+ #14 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 Call Trace: dump_stack+0xa5/0xe6 ubsan_epilogue+0x9/0x26 __ubsan_handle_load_invalid_value+0x6d/0x76 nullb_device_memory_backed_store.cold+0x2c/0x38 [null_blk] configfs_write_file+0x1c4/0x250 [configfs] __vfs_write+0x4c/0x90 vfs_write+0x145/0x2c0 ksys_write+0xd7/0x180 __x64_sys_write+0x47/0x50 do_syscall_64+0x6f/0x2f0 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Signed-off-by: Bart Van Assche bvanassche@acm.org Reviewed-by: Chaitanya Kulkarni chaitanya.kulkarni@wdc.com Cc: Johannes Thumshirn jth@kernel.org Cc: Hannes Reinecke hare@suse.com Cc: Ming Lei ming.lei@redhat.com Cc: Christoph Hellwig hch@infradead.org Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/null_blk_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c index d5b4a92033d48..2b8b4cb447cfb 100644 --- a/drivers/block/null_blk_main.c +++ b/drivers/block/null_blk_main.c @@ -276,7 +276,7 @@ nullb_device_##NAME##_store(struct config_item *item, const char *page, \ { \ int (*apply_fn)(struct nullb_device *dev, TYPE new_value) = APPLY;\ struct nullb_device *dev = to_nullb_device(item); \ - TYPE uninitialized_var(new_value); \ + TYPE new_value = 0; \ int ret; \ \ ret = nullb_device_##TYPE##_attr_store(&new_value, page, count);\