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| author | Rasmus Villemoes <linux@rasmusvillemoes.dk> | 2018-07-19 16:07:58 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-07-19 16:46:23 +0200 |
| commit | 8e974b3b8eddd42a8c43a18e8ea66a3e7b803a0d (patch) | |
| tree | a4f022326531962d53f7744e7d1460bbb0eebe47 /arch/x86/kernel/dumpstack.c | |
| parent | Linux 4.18-rc5 (diff) | |
| download | linux-8e974b3b8eddd42a8c43a18e8ea66a3e7b803a0d.tar.xz linux-8e974b3b8eddd42a8c43a18e8ea66a3e7b803a0d.zip | |
x86: Avoid pr_cont() in show_opcodes()
If concurrent printk() messages are emitted, then pr_cont() is making it
extremly hard to decode which part of the output belongs to what. See the
convoluted example at:
https://syzkaller.appspot.com/text?tag=CrashReport&x=139d342c400000
Avoid this by using a proper prefix for each line and by using %ph format
in show_opcodes() which emits the 'Code:' line in one go.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: joe@perches.com
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@suse.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/1532009278-5953-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp
Diffstat (limited to 'arch/x86/kernel/dumpstack.c')
| -rw-r--r-- | arch/x86/kernel/dumpstack.c | 28 |
1 files changed, 9 insertions, 19 deletions
diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 666a284116ac..9c8652974f8e 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -22,8 +22,6 @@ #include <asm/stacktrace.h> #include <asm/unwind.h> -#define OPCODE_BUFSIZE 64 - int panic_on_unrecovered_nmi; int panic_on_io_nmi; static int die_counter; @@ -93,26 +91,18 @@ 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; +#define PROLOGUE_SIZE 42 +#define EPILOGUE_SIZE 21 +#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE) 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]); + if (probe_kernel_read(opcodes, rip - PROLOGUE_SIZE, OPCODE_BUFSIZE)) { + printk("%sCode: Bad RIP value.\n", loglvl); + } else { + printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %" + __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes, + opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1); } - pr_cont("\n"); } void show_ip(struct pt_regs *regs, const char *loglvl) |