From 84667d4849b0e0a939a76f9f62d45fa3b4d59692 Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Fri, 11 Dec 2009 08:43:13 -0600 Subject: [PATCH] kgdb: Read buffer overflow Roel Kluin reported an error found with Parfait. Where we want to ensure that that kgdb_info[-1] never gets accessed. Also check to ensure any negative tid does not exceed the size of the shadow CPU array, else report critical debug context because it is an internal kgdb failure. Reported-by: Roel Kluin Signed-off-by: Jason Wessel --- kernel/kgdb.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/kgdb.c b/kernel/kgdb.c index 7d70146..29357a9 100644 --- a/kernel/kgdb.c +++ b/kernel/kgdb.c @@ -541,12 +541,17 @@ static struct task_struct *getthread(struct pt_regs *regs, int tid) */ if (tid == 0 || tid == -1) tid = -atomic_read(&kgdb_active) - 2; - if (tid < 0) { + if (tid < -1 && tid > -NR_CPUS - 2) { if (kgdb_info[-tid - 2].task) return kgdb_info[-tid - 2].task; else return idle_task(-tid - 2); } + if (tid <= 0) { + printk(KERN_ERR "KGDB: Internal thread select error\n"); + dump_stack(); + return NULL; + } /* * find_task_by_pid_ns() does not take the tasklist lock anymore -- 1.8.2.3