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authorChengfeng Ye <dg573847474@gmail.com>2023-07-28 15:39:01 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2023-08-04 16:05:56 +0300
commit8b66eec1fd85ca9c4fd83f92e704de4fc0c583c1 (patch)
tree1cba8c52fc5ee1c0700354dc40698a1d6e9114c0 /drivers/tty/synclink_gt.c
parentf68279ca7f806c44fbbae0a631e5603ba426d9be (diff)
downloadlinux-8b66eec1fd85ca9c4fd83f92e704de4fc0c583c1.tar.xz
tty: synclink_gt: Fix potential deadlock on &info->lock
As &info->lock is acquired by slgt_interrupt() under irq context, other process context code acquiring the lock should disable irq, otherwise deadlock could happen if the irq preempt the execution while the lock is held in process context on the same CPU. Lock acquisition inside set_params32() does not disable irq, and this function is called by slgt_compat_ioctl() from process context. Possible deadlock scenario: slgt_compat_ioctl() -> set_params32() -> spin_lock(&info->lock) <irq> -> slgt_interrupt() -> spin_lock(&info->lock); (deadlock here) This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock. x86_64 allmodconfig using gcc shows no new warning. The patch fixes the potential deadlock by spin_lock_irqsave() like other lock acquisition sites. Signed-off-by: Chengfeng Ye <dg573847474@gmail.com> Reviewed-by: Jiri Slaby <jirislaby@kernel.org> Link: https://lore.kernel.org/r/20230728123901.64225-1-dg573847474@gmail.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/synclink_gt.c')
-rw-r--r--drivers/tty/synclink_gt.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/tty/synclink_gt.c b/drivers/tty/synclink_gt.c
index fe53e9c2c9b4..4c6366fe015c 100644
--- a/drivers/tty/synclink_gt.c
+++ b/drivers/tty/synclink_gt.c
@@ -1087,12 +1087,13 @@ static long get_params32(struct slgt_info *info, struct MGSL_PARAMS32 __user *us
static long set_params32(struct slgt_info *info, struct MGSL_PARAMS32 __user *new_params)
{
struct MGSL_PARAMS32 tmp_params;
+ unsigned long flags;
DBGINFO(("%s set_params32\n", info->device_name));
if (copy_from_user(&tmp_params, new_params, sizeof(struct MGSL_PARAMS32)))
return -EFAULT;
- spin_lock(&info->lock);
+ spin_lock_irqsave(&info->lock, flags);
if (tmp_params.mode == MGSL_MODE_BASE_CLOCK) {
info->base_clock = tmp_params.clock_speed;
} else {
@@ -1110,7 +1111,7 @@ static long set_params32(struct slgt_info *info, struct MGSL_PARAMS32 __user *ne
info->params.stop_bits = tmp_params.stop_bits;
info->params.parity = tmp_params.parity;
}
- spin_unlock(&info->lock);
+ spin_unlock_irqrestore(&info->lock, flags);
program_hw(info);