Revert "firewire: Kill unnecessary buf check in device_attribute.show"
This reverts commit 4a2b06ca33763b363038d333274e212db6ff0de1.
The previous fix didn't consider callers from other than sysfs. Revert
it to fix the NULL dereference
kernel: ? sysfs_emit+0xb5/0xc0
kernel: show_immediate+0x13f/0x1d0 [firewire_core]
kernel: init_fw_attribute_group+0x81/0x150 [firewire_core]
kernel: create_units+0x119/0x160 [firewire_core]
kernel: fw_device_init+0x1a9/0x330 [firewire_core]
kernel: fw_device_workfn+0x12/0x20 [firewire_core]
kernel: process_one_work+0x16f/0x350
kernel: worker_thread+0x306/0x440
kernel: ? __pfx_worker_thread+0x10/0x10
kernel: kthread+0xf2/0x120
kernel: ? __pfx_kthread+0x10/0x10
kernel: ret_from_fork+0x47/0x70
kernel: ? __pfx_kthread+0x10/0x10
kernel: ret_from_fork_asm+0x1b/0x30
kernel: </TASK>
kernel: ---[ end trace 0000000000000000 ]---
kernel: ------------[ cut here ]------------
Fixes: 4a2b06ca3376 ("firewire: Kill unnecessary buf check in device_attribute.show")
Reported-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Link: https://lore.kernel.org/lkml/625470f3-b196-43f7-9844-fa1cb6da99f8@fujitsu.com/
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index c0976f6..f208a02 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -322,7 +322,7 @@
if (value < 0)
return -ENOENT;
- return sysfs_emit(buf, "0x%06x\n", value);
+ return buf ? sysfs_emit(buf, "0x%06x\n", value) : 0;
}
#define IMMEDIATE_ATTR(name, key) \
@@ -334,6 +334,8 @@
struct config_rom_attribute *attr =
container_of(dattr, struct config_rom_attribute, attr);
const u32 *directories[] = {NULL, NULL};
+ size_t bufsize;
+ char dummy_buf[2];
int i, ret = -ENOENT;
down_read(&fw_device_rwsem);
@@ -355,9 +357,15 @@
}
}
+ if (buf) {
+ bufsize = PAGE_SIZE - 1;
+ } else {
+ buf = dummy_buf;
+ bufsize = 1;
+ }
+
for (i = 0; i < ARRAY_SIZE(directories) && !!directories[i]; ++i) {
- int result = fw_csr_string(directories[i], attr->key, buf,
- PAGE_SIZE - 1);
+ int result = fw_csr_string(directories[i], attr->key, buf, bufsize);
// Detected.
if (result >= 0) {
ret = result;
@@ -366,7 +374,7 @@
// in the root directory follows to the directory entry for vendor ID
// instead of the immediate value for vendor ID.
result = fw_csr_string(directories[i], CSR_DIRECTORY | attr->key, buf,
- PAGE_SIZE - 1);
+ bufsize);
if (result >= 0)
ret = result;
}
