Corrected Signed-off-by: addresses. >From 96d9d4d135994a081e54d33d23f5007c53d9b5dd Mon Sep 17 00:00:00 2001 From: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Date: Tue, 17 Jul 2018 22:47:11 +0900 Subject: [PATCH v4] x86: Avoid pr_cont() in show_opcodes()
Since syzbot is confused by concurrent printk() messages [1], this patch changes show_opcodes() to use %*ph format string. When we start adding prefix to each line of printk() output, we will be able to handle concurrent printk() messages. [1] https://syzkaller.appspot.com/text?tag=CrashReport&x=139d342c400000 Signed-off-by: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp> Signed-off-by: Rasmus Villemoes <li...@rasmusvillemoes.dk> Cc: Borislav Petkov <b...@suse.de> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Josh Poimboeuf <jpoim...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Andy Lutomirski <l...@amacapital.net> --- arch/x86/kernel/dumpstack.c | 25 +++++++------------------ 1 file changed, 7 insertions(+), 18 deletions(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 666a284..ffdd484 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -93,26 +93,15 @@ static void printk_stack_address(unsigned long address, int reliable, */ void show_opcodes(u8 *rip, const char *loglvl) { - unsigned int code_prologue = OPCODE_BUFSIZE * 2 / 3; + const unsigned int prologue = OPCODE_BUFSIZE * 2 / 3; u8 opcodes[OPCODE_BUFSIZE]; - u8 *ip; - int i; - printk("%sCode: ", loglvl); - - ip = (u8 *)rip - code_prologue; - if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) { - pr_cont("Bad RIP value.\n"); - return; - } - - for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) { - if (ip == rip) - pr_cont("<%02x> ", opcodes[i]); - else - pr_cont("%02x ", opcodes[i]); - } - pr_cont("\n"); + if (probe_kernel_read(opcodes, rip - prologue, OPCODE_BUFSIZE)) + printk("%sCode: Bad RIP value.\n", loglvl); + else + printk("%sCode: %*ph <%02x> %*ph\n", loglvl, prologue, opcodes, + opcodes[prologue], OPCODE_BUFSIZE - prologue - 1, + &opcodes[prologue + 1]); } void show_ip(struct pt_regs *regs, const char *loglvl) -- 1.8.3.1
