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signal/powerpc: On swapcontext failure force SIGSEGV

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If the register state may be partial and corrupted instead of calling
do_exit, call force_sigsegv(SIGSEGV).  Which properly kills the
process with SIGSEGV and does not let any more userspace code execute,
instead of just killing one thread of the process and potentially
confusing everything.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Fixes: 756f1ae8a44e ("PPC32: Rework signal code and add a swapcontext system call.")
Fixes: 04879b04bf50 ("[PATCH] ppc64: VMX (Altivec) support & signal32 rework, from Ben Herrenschmidt")
Link: https://lkml.kernel.org/r/20211020174406.17889-7-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2021-10-20 12:43:53 -05:00
parent ce0ee4e6ac
commit 83a1f27ad7
2 changed files with 10 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
arch/powerpc/kernel/signal_32.c
View file

@ -1062,8 +1062,10 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
* or if another thread unmaps the region containing the context.
* We kill the task with a SIGSEGV in this situation.
*/
if (do_setcontext(new_ctx, regs, 0))
do_exit(SIGSEGV);
if (do_setcontext(new_ctx, regs, 0)) {
force_sigsegv(SIGSEGV);
return -EFAULT;
}
set_thread_flag(TIF_RESTOREALL);
return 0;

9
arch/powerpc/kernel/signal_64.c
View file

@ -703,15 +703,18 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *, old_ctx,
* We kill the task with a SIGSEGV in this situation.
*/
if (__get_user_sigset(&set, &new_ctx->uc_sigmask))
do_exit(SIGSEGV);
if (__get_user_sigset(&set, &new_ctx->uc_sigmask)) {
force_sigsegv(SIGSEGV);
return -EFAULT;
}
set_current_blocked(&set);
if (!user_read_access_begin(new_ctx, ctx_size))
return -EFAULT;
if (__unsafe_restore_sigcontext(current, NULL, 0, &new_ctx->uc_mcontext)) {
user_read_access_end();
do_exit(SIGSEGV);
force_sigsegv(SIGSEGV);
return -EFAULT;
}
user_read_access_end();