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authorTaku Izumi <izumi2005@soft.fujitsu.com>2007-04-23 14:41:00 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2007-05-01 17:06:01 -0700
commitaad6bcca0b1ca356ede42583c96dc7ada541cffe (patch)
treede1b679f5172a0fc2aa8532a843b270e69f1a2a3
parent8505260d098b10600044268568ef851419946c33 (diff)
Fix possible NULL pointer access in 8250 serial driver
I encountered the following kernel panic. The cause of this problem was NULL pointer access in check_modem_status() in 8250.c. I confirmed this problem is fixed by the attached patch, but I don't know this is the correct fix. sadc[4378]: NaT consumption 2216203124768 [1] Modules linked in: binfmt_misc dm_mirror dm_mod thermal processor fan container button sg e100 eepro100 mii ehci_hcd ohci_hcd Pid: 4378, CPU 0, comm: sadc psr : 00001210085a2010 ifs : 8000000000000289 ip : [<a000000100482071>] Not tainted ip is at check_modem_status+0xf1/0x360 unat: 0000000000000000 pfs : 0000000000000289 rsc : 0000000000000003 rnat: 800000000000cc18 bsps: 0000000000000000 pr : 0000000000aa6a99 ldrs: 0000000000000000 ccv : 0000000000000000 fpsr: 0009804c8a70033f csd : 0000000000000000 ssd : 0000000000000000 b0 : a000000100481fb0 b6 : a0000001004822e0 b7 : a000000100477f20 f6 : 1003e2222222222222222 f7 : 0ffdba200000000000000 f8 : 100018000000000000000 f9 : 10002a000000000000000 f10 : 0fffdccccccccc8c00000 f11 : 1003e0000000000000000 r1 : a000000100b9af40 r2 : 0000000000000008 r3 : a000000100ad4e21 r8 : 00000000000000bb r9 : 0000000000000001 r10 : 0000000000000000 r11 : a000000100ad4d58 r12 : e0000000037b7df0 r13 : e0000000037b0000 r14 : 0000000000000001 r15 : 0000000000000018 r16 : a000000100ad4d6c r17 : 0000000000000000 r18 : 0000000000000000 r19 : 0000000000000000 r20 : a00000010099bc88 r21 : 00000000000000bb r22 : 00000000000000bb r23 : c003fffffc0ff3fe r24 : c003fffffc000000 r25 : 00000000000ff3fe r26 : a0000001009b7ad0 r27 : 0000000000000001 r28 : a0000001009b7ad8 r29 : 0000000000000000 r30 : a0000001009b7ad0 r31 : a0000001009b7ad0 Call Trace: [<a000000100013940>] show_stack+0x40/0xa0 sp=e0000000037b7810 bsp=e0000000037b1118 [<a0000001000145a0>] show_regs+0x840/0x880 sp=e0000000037b79e0 bsp=e0000000037b10c0 [<a0000001000368e0>] die+0x1c0/0x2c0 sp=e0000000037b79e0 bsp=e0000000037b1078 [<a000000100036a30>] die_if_kernel+0x50/0x80 sp=e0000000037b7a00 bsp=e0000000037b1048 [<a000000100037c40>] ia64_fault+0x11e0/0x1300 sp=e0000000037b7a00 bsp=e0000000037b0fe8 [<a00000010000bdc0>] ia64_leave_kernel+0x0/0x280 sp=e0000000037b7c20 bsp=e0000000037b0fe8 [<a000000100482070>] check_modem_status+0xf0/0x360 sp=e0000000037b7df0 bsp=e0000000037b0fa0 [<a000000100482300>] serial8250_get_mctrl+0x20/0xa0 sp=e0000000037b7df0 bsp=e0000000037b0f80 [<a000000100478170>] uart_read_proc+0x250/0x860 sp=e0000000037b7df0 bsp=e0000000037b0ee0 [<a0000001001c16d0>] proc_file_read+0x1d0/0x4c0 sp=e0000000037b7e10 bsp=e0000000037b0e80 [<a0000001001394b0>] vfs_read+0x1b0/0x300 sp=e0000000037b7e20 bsp=e0000000037b0e30 [<a000000100139cd0>] sys_read+0x70/0xe0 sp=e0000000037b7e20 bsp=e0000000037b0db0 [<a00000010000bc20>] ia64_ret_from_syscall+0x0/0x20 sp=e0000000037b7e30 bsp=e0000000037b0db0 [<a000000000010620>] __kernel_syscall_via_break+0x0/0x20 sp=e0000000037b8000 bsp=e0000000037b0db0 Fix the possible NULL pointer access in check_modem_status() in 8250.c. The check_modem_status() would access 'info' member of uart_port structure, but it is not initialized before uart_open() is called. The check_modem_status() can be called through /proc/tty/driver/serial before uart_open() is called. Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com> Signed-off-by: Taku Izumi <izumi2005@soft.fujitsu.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/serial/8250.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 5261f0af8b10..2e542b97593b 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1289,7 +1289,8 @@ static unsigned int check_modem_status(struct uart_8250_port *up)
{
unsigned int status = serial_in(up, UART_MSR);
- if (status & UART_MSR_ANY_DELTA && up->ier & UART_IER_MSI) {
+ if (status & UART_MSR_ANY_DELTA && up->ier & UART_IER_MSI &&
+ up->port.info != NULL) {
if (status & UART_MSR_TERI)
up->port.icount.rng++;
if (status & UART_MSR_DDSR)