From: Tetsuo Handa <penguin-ker...@i-love.skaura.ne.jp> Since syzbot is confused by concurrent printk() messages [1], this patch changes show_opcodes() to use snprintf().
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.skaura.ne.jp> 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 | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 666a284..bb47426 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -97,22 +97,24 @@ void show_opcodes(u8 *rip, const char *loglvl) u8 opcodes[OPCODE_BUFSIZE]; u8 *ip; int i; - - printk("%sCode: ", loglvl); + int pos = 0; + char buf[(3 * OPCODE_BUFSIZE + 2) + 1]; ip = (u8 *)rip - code_prologue; if (probe_kernel_read(opcodes, ip, OPCODE_BUFSIZE)) { - pr_cont("Bad RIP value.\n"); + printk("%sCode: Bad RIP value.\n", loglvl); return; } for (i = 0; i < OPCODE_BUFSIZE; i++, ip++) { if (ip == rip) - pr_cont("<%02x> ", opcodes[i]); + pos += snprintf(buf + pos, sizeof(buf) - pos, + "<%02x> ", opcodes[i]); else - pr_cont("%02x ", opcodes[i]); + pos += snprintf(buf + pos, sizeof(buf) - pos, + "%02x ", opcodes[i]); } - pr_cont("\n"); + printk("%sCode: %s\n", loglvl, buf); } void show_ip(struct pt_regs *regs, const char *loglvl) -- 2.7.4
