diff options
| author | Elena Reshetova <elena.reshetova@intel.com> | 2017-03-06 16:21:15 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-03-14 11:01:40 +0800 |
| commit | 22a33651a56fa2a66339db059dcc247aa7131ced (patch) | |
| tree | b2f88df9ef5133a74ed90a26870ca5c6a96587ef /drivers/tty/serial | |
| parent | 8961df8950b1235cb7594e143a31bcc63757b660 (diff) | |
drivers: convert sbd_duart.map_guard from atomic_t to refcount_t
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/serial')
| -rw-r--r-- | drivers/tty/serial/sb1250-duart.c | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/drivers/tty/serial/sb1250-duart.c b/drivers/tty/serial/sb1250-duart.c index 771f361c47ea..041625cc24bb 100644 --- a/drivers/tty/serial/sb1250-duart.c +++ b/drivers/tty/serial/sb1250-duart.c @@ -41,7 +41,7 @@ #include <linux/tty_flip.h> #include <linux/types.h> -#include <linux/atomic.h> +#include <linux/refcount.h> #include <asm/io.h> #include <asm/war.h> @@ -103,7 +103,7 @@ struct sbd_port { struct sbd_duart { struct sbd_port sport[2]; unsigned long mapctrl; - atomic_t map_guard; + refcount_t map_guard; }; #define to_sport(uport) container_of(uport, struct sbd_port, port) @@ -654,15 +654,13 @@ static void sbd_release_port(struct uart_port *uport) { struct sbd_port *sport = to_sport(uport); struct sbd_duart *duart = sport->duart; - int map_guard; iounmap(sport->memctrl); sport->memctrl = NULL; iounmap(uport->membase); uport->membase = NULL; - map_guard = atomic_add_return(-1, &duart->map_guard); - if (!map_guard) + if(refcount_dec_and_test(&duart->map_guard)) release_mem_region(duart->mapctrl, DUART_CHANREG_SPACING); release_mem_region(uport->mapbase, DUART_CHANREG_SPACING); } @@ -698,7 +696,6 @@ static int sbd_request_port(struct uart_port *uport) { const char *err = KERN_ERR "sbd: Unable to reserve MMIO resource\n"; struct sbd_duart *duart = to_sport(uport)->duart; - int map_guard; int ret = 0; if (!request_mem_region(uport->mapbase, DUART_CHANREG_SPACING, @@ -706,11 +703,11 @@ static int sbd_request_port(struct uart_port *uport) printk(err); return -EBUSY; } - map_guard = atomic_add_return(1, &duart->map_guard); - if (map_guard == 1) { + refcount_inc(&duart->map_guard); + if (refcount_read(&duart->map_guard) == 1) { if (!request_mem_region(duart->mapctrl, DUART_CHANREG_SPACING, "sb1250-duart")) { - atomic_add(-1, &duart->map_guard); + refcount_dec(&duart->map_guard); printk(err); ret = -EBUSY; } @@ -718,8 +715,7 @@ static int sbd_request_port(struct uart_port *uport) if (!ret) { ret = sbd_map_port(uport); if (ret) { - map_guard = atomic_add_return(-1, &duart->map_guard); - if (!map_guard) + if (refcount_dec_and_test(&duart->map_guard)) release_mem_region(duart->mapctrl, DUART_CHANREG_SPACING); } |