Avoid dereferencing a NULL pointer when TCP_REASS_LOGGING is enabled

[tuexen]

Summary

This patch addresses an issue brought up by bz@ in D18968: When TCP_REASS_LOGGING is defined (which doesn't compile right now), a NULL pointer dereference would happen, if user data was received during the TCP handshake and BB logging is used.

A KASSERT is also added to detect tcp_reass() calls with illegal parameter combinations.

[bz]

sys/netinet/tcp_reass.c

547 ↗

(On Diff #54094)

Please add %p and others to the printf so people will be able to have pointers to the tp, th, ..., m for debugging in case this fires.
Will also help them to find out which illegal combination it was.

[tuexen]

Address bz@'s comment.

[tuexen]

sys/netinet/tcp_reass.c

547 ↗

(On Diff #54094)

Good suggestion.Diff updated.

head/sys/netinet/tcp_reass.c

#ifdef KDB
         if (debugger_on_trap) {
                 kdb_why = KDB_WHY_TRAP;
                 handled = kdb_trap(frame->tf_scause & SCAUSE_CODE, 0, frame);
                 kdb_why = KDB_WHY_UNSET;
                 if (handled)
                         return;
         }
 #endif
-        panic("Fatal page fault at %#lx: %#016lx", frame->tf_sepc, stval);
+        panic("Fatal page fault at %#lx: %#lx", frame->tf_sepc, stval);
 }
 
 void
 do_trap_supervisor(struct trapframe *frame)
 {
         uint64_t exception;
 
         /* Ensure we came from supervisor mode, interrupts disabled */
if ((frame->tf_scause & SCAUSE_INTR) != 0) {
                 return;
         }
 
 #ifdef KDTRACE_HOOKS
         if (dtrace_trap_func != NULL && (*dtrace_trap_func)(frame, exception))
                 return;
 #endif
 
-        CTR4(KTR_TRAP, "%s: exception=%lu, sepc=%lx, stval=%lx", __func__,
+        CTR4(KTR_TRAP, "%s: exception=%lu, sepc=%#lx, stval=%#lx", __func__,
             exception, frame->tf_sepc, frame->tf_stval);
 
         switch (exception) {
         case SCAUSE_LOAD_ACCESS_FAULT:
         case SCAUSE_STORE_ACCESS_FAULT:
         case SCAUSE_INST_ACCESS_FAULT:
                 dump_regs(frame);
-                panic("Memory access exception at 0x%016lx\n", frame->tf_sepc);
+                panic("Memory access exception at %#lx: %#lx",
+                    frame->tf_sepc, frame->tf_stval);
                 break;
         case SCAUSE_LOAD_MISALIGNED:
         case SCAUSE_STORE_MISALIGNED:
         case SCAUSE_INST_MISALIGNED:
                 dump_regs(frame);
-                panic("Misaligned address exception at %#016lx: %#016lx\n",
+                panic("Misaligned address exception at %#lx: %#lx",
                     frame->tf_sepc, frame->tf_stval);
                 break;
         case SCAUSE_STORE_PAGE_FAULT:
         case SCAUSE_LOAD_PAGE_FAULT:
         case SCAUSE_INST_PAGE_FAULT:
                 page_fault_handler(frame, 0);
                 break;
         case SCAUSE_BREAKPOINT:
 #ifdef KDTRACE_HOOKS
                 if (dtrace_invop_jump_addr != NULL &&
                     dtrace_invop_jump_addr(frame) == 0)
                                 break;
 #endif
 #ifdef KDB
                 kdb_trap(exception, 0, frame);
 #else
                 dump_regs(frame);
-                panic("No debugger in kernel.\n");
+                panic("No debugger in kernel.");
 #endif
                 break;
         case SCAUSE_ILLEGAL_INSTRUCTION:
                 dump_regs(frame);
-                panic("Illegal instruction at 0x%016lx\n", frame->tf_sepc);
+                panic("Illegal instruction %#lx at %#lx", frame->tf_stval,
+                    frame->tf_sepc);
                 break;
         default:
                 dump_regs(frame);
-                panic("Unknown kernel exception %lx trap value %lx\n",
+                panic("Unknown kernel exception %#lx trap value %#lx",
                     exception, frame->tf_stval);
         }
 }
 
 void
 do_trap_user(struct trapframe *frame)
 {
         uint64_t exception;
do_trap_user(struct trapframe *frame)
         exception = frame->tf_scause & SCAUSE_CODE;
         if ((frame->tf_scause & SCAUSE_INTR) != 0) {
                 /* Interrupt */
                 riscv_cpu_intr(frame);
                 return;
         }
         intr_enable();
 
-        CTR4(KTR_TRAP, "%s: exception=%lu, sepc=%lx, stval=%lx", __func__,
+        CTR4(KTR_TRAP, "%s: exception=%lu, sepc=%#lx, stval=%#lx", __func__,
             exception, frame->tf_sepc, frame->tf_stval);
 
         switch (exception) {
         case SCAUSE_LOAD_ACCESS_FAULT:
         case SCAUSE_STORE_ACCESS_FAULT:
         case SCAUSE_INST_ACCESS_FAULT:
                 call_trapsignal(td, SIGBUS, BUS_ADRERR, (void *)frame->tf_sepc,
                     exception);
case SCAUSE_ILLEGAL_INSTRUCTION:
                 break;
         case SCAUSE_BREAKPOINT:
                 call_trapsignal(td, SIGTRAP, TRAP_BRKPT, (void *)frame->tf_sepc,
                     exception);
                 userret(td, frame);
                 break;
         default:
                 dump_regs(frame);
-                panic("Unknown userland exception %lx, trap value %lx\n",
+                panic("Unknown userland exception %#lx, trap value %#lx",
                     exception, frame->tf_stval);
         }
 }