From 0405e128110d47a40443936e68dc32d7bc4ccc0b Mon Sep 17 00:00:00 2001 From: Madhavan Srinivasan Date: Mon, 26 Aug 2024 12:12:17 +0530 Subject: [PATCH] powerpc/xmon: Fix tmpstr length check in scanhex If a function name is greater than 63 characters long, xmon command may not find them. For example, here is a test that executed an illegal instruction in a kernel function and one of call stack function has a name greater than 63 characters long: cpu 0x0: Vector: 700 (Program Check) at [c00000000a6577e0] pc: c0000000001aacb8: check__allowed__function__name__for__symbol__r4+0x8/0x10 lr: c00000000019c1e0: check__allowed__function__name__for__symbol__r1+0x20/0x40 sp: c00000000a657a80 msr: 800000000288b033 current = 0xc00000000a439900 paca = 0xc000000003e90000 irqmask: 0x03 irq_happened: 0x01 ..... [link register ] c00000000019c1e0 check__allowed__function__name__for__symbol__r1+0x20/0x40 [c00000000a657a80] c00000000a439900 (unreliable) [c00000000a657aa0] c0000000001021d8 check__allowed__function__name__for__symbol__r2_resolution_symbol+0x38/0x4c [c00000000a657ac0] c00000000019b424 power_pmu_event_init+0xa4/0xa50 and when executing a dump instruction (di) command for long function name, xmon fails to find the function symbol: 0:mon> di $check__allowed__function__name__for__symbol__r2_resolution_symbol unknown symbol 'check__allowed__function__name__for__symbol__r2_resolution_symb' 0000000000000000 ******** This is because in scanhex(), tmpstr loop index is checked only for a upper bound of 63. Fix it by replacing the upper bound value with (KSYM_NAME_LEN-1). With fix: 0:mon> di $check__allowed__function__name__for__symbol__r2_resolution_symbol c0000000001021a0 3c4c0249 addis r2,r12,585 c0000000001021a4 3842ae60 addi r2,r2,-20896 c0000000001021a8 7c0802a6 mflr r0 c0000000001021ac 60000000 nop ..... Reported-by: Miguel Ojeda Closes: https://lore.kernel.org/linuxppc-dev/CANiq72=QeTgtZL4k9=4CJP6C_Hv=rh3fsn3B9S3KFoPXkyWk3w@mail.gmail.com/ Signed-off-by: Madhavan Srinivasan Signed-off-by: Michael Ellerman Link: https://msgid.link/20240826064217.46658-1-maddy@linux.ibm.com --- arch/powerpc/xmon/xmon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index bd4813bad317..e6cddbb2305f 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -3543,7 +3543,7 @@ scanhex(unsigned long *vp) } } else if (c == '$') { int i; - for (i=0; i<63; i++) { + for (i = 0; i < (KSYM_NAME_LEN - 1); i++) { c = inchar(); if (isspace(c) || c == '\0') { termch = c;