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authorTaku Izumi <izumi2005@soft.fujitsu.com>2007-04-23 14:41:00 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-04-24 08:23:07 -0700
commitfdc30b3d448bf86dd45f9df3e8ac0d36a3bdd9b2 (patch)
treee434f6c805916d51f288d2e4848a5e86b374edc1 /drivers/serial/8250.c
parent650a7c974f1b91de9732c0f720e792837f8abfd6 (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 Call Trace: [<a000000100013940>] show_stack+0x40/0xa0 [<a0000001000145a0>] show_regs+0x840/0x880 [<a0000001000368e0>] die+0x1c0/0x2c0 [<a000000100036a30>] die_if_kernel+0x50/0x80 [<a000000100037c40>] ia64_fault+0x11e0/0x1300 [<a00000010000bdc0>] ia64_leave_kernel+0x0/0x280 [<a000000100482070>] check_modem_status+0xf0/0x360 [<a000000100482300>] serial8250_get_mctrl+0x20/0xa0 [<a000000100478170>] uart_read_proc+0x250/0x860 [<a0000001001c16d0>] proc_file_read+0x1d0/0x4c0 [<a0000001001394b0>] vfs_read+0x1b0/0x300 [<a000000100139cd0>] sys_read+0x70/0xe0 [<a00000010000bc20>] ia64_ret_from_syscall+0x0/0x20 [<a000000000010620>] __kernel_syscall_via_break+0x0/0x20 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> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/serial/8250.c')
-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 c129a0e8e80..c0c472ac531 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -1310,7 +1310,8 @@ 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)