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authorMadhuparna Bhowmik <madhuparnabhowmik10@gmail.com>2020-04-17 21:04:51 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2020-04-23 16:55:24 +0200
commit44b8fb6eaa7c3fb770bf1e37619cdb3902cca1fc (patch)
tree9d65c3a0c35a7f41609eb40805456f93fdb3e710
parentc18c1f103503981bfbb3b9c3cdf3d2ea14f8e010 (diff)
drivers: char: tlclk.c: Avoid data race between init and interrupt handler
After registering character device the file operation callbacks can be called. The open callback registers interrupt handler. Therefore interrupt handler can execute in parallel with rest of the init function. To avoid such data race initialize telclk_interrupt variable and struct alarm_events before registering character device. Found by Linux Driver Verification project (linuxtesting.org). Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> Link: https://lore.kernel.org/r/20200417153451.1551-1-madhuparnabhowmik10@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/char/tlclk.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/drivers/char/tlclk.c b/drivers/char/tlclk.c
index 6d81bb3bb503..896a3550fba9 100644
--- a/drivers/char/tlclk.c
+++ b/drivers/char/tlclk.c
@@ -777,17 +777,21 @@ static int __init tlclk_init(void)
{
int ret;
+ telclk_interrupt = (inb(TLCLK_REG7) & 0x0f);
+
+ alarm_events = kzalloc( sizeof(struct tlclk_alarms), GFP_KERNEL);
+ if (!alarm_events) {
+ ret = -ENOMEM;
+ goto out1;
+ }
+
ret = register_chrdev(tlclk_major, "telco_clock", &tlclk_fops);
if (ret < 0) {
printk(KERN_ERR "tlclk: can't get major %d.\n", tlclk_major);
+ kfree(alarm_events);
return ret;
}
tlclk_major = ret;
- alarm_events = kzalloc( sizeof(struct tlclk_alarms), GFP_KERNEL);
- if (!alarm_events) {
- ret = -ENOMEM;
- goto out1;
- }
/* Read telecom clock IRQ number (Set by BIOS) */
if (!request_region(TLCLK_BASE, 8, "telco_clock")) {
@@ -796,7 +800,6 @@ static int __init tlclk_init(void)
ret = -EBUSY;
goto out2;
}
- telclk_interrupt = (inb(TLCLK_REG7) & 0x0f);
if (0x0F == telclk_interrupt ) { /* not MCPBL0010 ? */
printk(KERN_ERR "telclk_interrupt = 0x%x non-mcpbl0010 hw.\n",
@@ -837,8 +840,8 @@ out3:
release_region(TLCLK_BASE, 8);
out2:
kfree(alarm_events);
-out1:
unregister_chrdev(tlclk_major, "telco_clock");
+out1:
return ret;
}