4.4-stable review patch. If anyone has any objections, please let me know.
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From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit fc14eebfc20854a38fd9f1d93a42b1783dad4d17 upstream.
syzbot is reporting NULL pointer dereference at snapshot_write() [1]. This is because data->handle is zero-cleared by ioctl(SNAPSHOT_FREE). Fix this by checking data_of(data->handle) != NULL before using it.
[1] https://syzkaller.appspot.com/bug?id=828a3c71bd344a6de8b6a31233d51a72099f27f...
Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Reported-by: syzbot syzbot+ae590932da6e45d6564d@syzkaller.appspotmail.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- kernel/power/user.c | 5 +++++ 1 file changed, 5 insertions(+)
--- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -184,6 +184,11 @@ static ssize_t snapshot_write(struct fil res = PAGE_SIZE - pg_offp; }
+ if (!data_of(data->handle)) { + res = -EINVAL; + goto unlock; + } + res = simple_write_to_buffer(data_of(data->handle), res, &pg_offp, buf, count); if (res > 0)