mips o32: do not bail out in get_syscall_args if umoven fails

If the kernel contains commit 84d77d3f06e7e8dea057d10e8ec77ad71f721be3,
both PTRACE_PEEKDATA and process_vm_readv become unavailable when the
process dumpable flag is cleared.  As the first 4 syscall arguments are
still available via registers, do not treat this as get_syscall_args
error.

This condition is triggered and therefore tested by prctl-dumpable test.

* linux/mips/get_syscall_args.c (get_syscall_args) [LINUX_MIPSO32]:
Do not bail out if umoven fails.

diff --git a/linux/mips/get_syscall_args.c b/linux/mips/get_syscall_args.c
index ca2819bf375fe1207308cf85070de6d4988db5be..3c9160e3f852c5b85ecc883fb19cb60c01b277d0 100644 (file)
--- a/linux/mips/get_syscall_args.c
+++ b/linux/mips/get_syscall_args.c
@@ -14,11 +14,16 @@ get_syscall_args(struct tcb *tcp)
        tcp->u_arg[1] = mips_REG_A1;
        tcp->u_arg[2] = mips_REG_A2;
        tcp->u_arg[3] = mips_REG_A3;
-       if (tcp->s_ent->nargs > 4) {
-               if (umoven(tcp, mips_REG_SP + 4 * 4,
-                          (tcp->s_ent->nargs - 4) * sizeof(tcp->u_arg[0]),
-                          &tcp->u_arg[4]) < 0)
-                       return -1;
+       if (tcp->s_ent->nargs > 4
+           && umoven(tcp, mips_REG_SP + 4 * sizeof(tcp->u_arg[0]),
+                     (tcp->s_ent->nargs - 4) * sizeof(tcp->u_arg[0]),
+                     &tcp->u_arg[4]) < 0) {
+               /*
+                * Let's proceed with the first 4 arguments
+                * instead of reporting the failure.
+                */
+               memset(&tcp->u_arg[4], 0,
+                      (tcp->s_ent->nargs - 4) * sizeof(tcp->u_arg[0]));
        }
 #else
 # error unsupported mips abi