[ Upstream commit 5caaf29af5ca82d5da8bc1d0ad07d9e664ccf1d8 ]
If spi_register_master fails in spi_bitbang_start because device_add failure, We should return the error code other than 0, otherwise calling spi_bitbang_stop may trigger NULL pointer dereference like this:
BUG: KASAN: null-ptr-deref in __list_del_entry_valid+0x45/0xd0 Read of size 8 at addr 0000000000000000 by task syz-executor.0/3661
CPU: 0 PID: 3661 Comm: syz-executor.0 Not tainted 5.1.0+ #28 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: dump_stack+0xa9/0x10e ? __list_del_entry_valid+0x45/0xd0 ? __list_del_entry_valid+0x45/0xd0 __kasan_report+0x171/0x18d ? __list_del_entry_valid+0x45/0xd0 kasan_report+0xe/0x20 __list_del_entry_valid+0x45/0xd0 spi_unregister_controller+0x99/0x1b0 spi_lm70llp_attach+0x3ae/0x4b0 [spi_lm70llp] ? 0xffffffffc1128000 ? klist_next+0x131/0x1e0 ? driver_detach+0x40/0x40 [parport] port_check+0x3b/0x50 [parport] bus_for_each_dev+0x115/0x180 ? subsys_dev_iter_exit+0x20/0x20 __parport_register_driver+0x1f0/0x210 [parport] ? 0xffffffffc1150000 do_one_initcall+0xb9/0x3b5 ? perf_trace_initcall_level+0x270/0x270 ? kasan_unpoison_shadow+0x30/0x40 ? kasan_unpoison_shadow+0x30/0x40 do_init_module+0xe0/0x330 load_module+0x38eb/0x4270 ? module_frob_arch_sections+0x20/0x20 ? kernel_read_file+0x188/0x3f0 ? find_held_lock+0x6d/0xd0 ? fput_many+0x1a/0xe0 ? __do_sys_finit_module+0x162/0x190 __do_sys_finit_module+0x162/0x190 ? __ia32_sys_init_module+0x40/0x40 ? __mutex_unlock_slowpath+0xb4/0x3f0 ? wait_for_completion+0x240/0x240 ? vfs_write+0x160/0x2a0 ? lockdep_hardirqs_off+0xb5/0x100 ? mark_held_locks+0x1a/0x90 ? do_syscall_64+0x14/0x2a0 do_syscall_64+0x72/0x2a0 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Reported-by: Hulk Robot hulkci@huawei.com Fixes: 702a4879ec33 ("spi: bitbang: Let spi_bitbang_start() take a reference to master") Signed-off-by: YueHaibing yuehaibing@huawei.com Reviewed-by: Geert Uytterhoeven geert+renesas@glider.be Reviewed-by: Axel Lin axel.lin@ingics.com Reviewed-by: Mukesh Ojha mojha@codeaurora.org Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi-bitbang.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c index f29176000b8d..06cf9388e74f 100644 --- a/drivers/spi/spi-bitbang.c +++ b/drivers/spi/spi-bitbang.c @@ -416,7 +416,7 @@ int spi_bitbang_start(struct spi_bitbang *bitbang) if (ret) spi_master_put(master);
- return 0; + return ret; } EXPORT_SYMBOL_GPL(spi_bitbang_start);