From bb3ba35f20a42941140676264a41525efac984d9 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Mon, 16 Apr 2018 16:19:23 +0100 Subject: linux-user: check that all of AArch64 SVE extended sigframe is writable In commit 8c5931de0ac7738809 we added support for SVE extended sigframe records. These mean that the signal frame might now be larger than the size of the target_rt_sigframe record, so make sure we call lock_user on the entire frame size when we're creating it. (The code for restoring the signal frame already correctly handles the extended records by locking the 'extra' section separately to the main section.) In particular, this fixes a bug even for non-SVE signal frames, because it extends the locked section to cover the target_rt_frame_record. Previously this was part of 'struct target_rt_sigframe', but in commit e1eecd1d9d4c1ade3 we pulled it out into its own struct, and so locking the target_rt_sigframe alone doesn't cover it. This bug would mean that we would fail to correctly handle the case where a signal was taken with SP pointing 16 bytes into an unwritable page, with the page immediately below it in memory being writable. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson --- linux-user/signal.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'linux-user') diff --git a/linux-user/signal.c b/linux-user/signal.c index e6dfe0adfd..b283270391 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -1858,7 +1858,8 @@ static void target_setup_frame(int usig, struct target_sigaction *ka, frame_addr = get_sigframe(ka, env, layout.total_size); trace_user_setup_frame(env, frame_addr); - if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { + frame = lock_user(VERIFY_WRITE, frame_addr, layout.total_size, 0); + if (!frame) { goto give_sigsegv; } @@ -1904,11 +1905,11 @@ static void target_setup_frame(int usig, struct target_sigaction *ka, env->xregs[2] = frame_addr + offsetof(struct target_rt_sigframe, uc); } - unlock_user_struct(frame, frame_addr, 1); + unlock_user(frame, frame_addr, layout.total_size); return; give_sigsegv: - unlock_user_struct(frame, frame_addr, 1); + unlock_user(frame, frame_addr, layout.total_size); force_sigsegv(usig); } -- cgit v1.2.1