diff options
Diffstat (limited to 'arch/x86/kernel/signal.c')
| -rw-r--r-- | arch/x86/kernel/signal.c | 35 |
1 files changed, 31 insertions, 4 deletions
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c index 0111a6ae6e60..ec71e06ae364 100644 --- a/arch/x86/kernel/signal.c +++ b/arch/x86/kernel/signal.c @@ -32,6 +32,7 @@ #include <asm/processor.h> #include <asm/ucontext.h> #include <asm/fpu/signal.h> +#include <asm/fpu/xstate.h> #include <asm/vdso.h> #include <asm/mce.h> #include <asm/sighandling.h> @@ -720,12 +721,15 @@ badframe: /* max_frame_size tells userspace the worst case signal stack size. */ static unsigned long __ro_after_init max_frame_size; +static unsigned int __ro_after_init fpu_default_state_size; void __init init_sigframe_size(void) { + fpu_default_state_size = fpu__get_fpstate_size(); + max_frame_size = MAX_FRAME_SIGINFO_UCTXT_SIZE + MAX_FRAME_PADDING; - max_frame_size += fpu__get_fpstate_size() + MAX_XSAVE_PADDING; + max_frame_size += fpu_default_state_size + MAX_XSAVE_PADDING; /* Userspace expects an aligned size. */ max_frame_size = round_up(max_frame_size, FRAME_ALIGNMENT); @@ -928,15 +932,38 @@ __setup("strict_sas_size", strict_sas_size); * sigaltstack they just continued to work. While always checking against * the real size would be correct, this might be considered a regression. * - * Therefore avoid the sanity check, unless enforced by kernel config or - * command line option. + * Therefore avoid the sanity check, unless enforced by kernel + * configuration or command line option. + * + * When dynamic FPU features are supported, the check is also enforced when + * the task has permissions to use dynamic features. Tasks which have no + * permission are checked against the size of the non-dynamic feature set + * if strict checking is enabled. This avoids forcing all tasks on the + * system to allocate large sigaltstacks even if they are never going + * to use a dynamic feature. As this is serialized via sighand::siglock + * any permission request for a dynamic feature either happened already + * or will see the newly install sigaltstack size in the permission checks. */ bool sigaltstack_size_valid(size_t ss_size) { + unsigned long fsize = max_frame_size - fpu_default_state_size; + u64 mask; + lockdep_assert_held(¤t->sighand->siglock); + if (!fpu_state_size_dynamic() && !strict_sigaltstack_size) + return true; + + fsize += current->group_leader->thread.fpu.perm.__user_state_size; + if (likely(ss_size > fsize)) + return true; + if (strict_sigaltstack_size) - return ss_size > get_sigframe_size(); + return ss_size > fsize; + + mask = current->group_leader->thread.fpu.perm.__state_perm; + if (mask & XFEATURE_MASK_USER_DYNAMIC) + return ss_size > fsize; return true; } |