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| author | Colin Ian King <colin.king@canonical.com> | 2020-10-29 15:11:03 +0000 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2020-11-10 18:38:49 +0100 |
| commit | 8d4d9c7b4333abccb3bf310d76ef7ea2edb9828f (patch) | |
| tree | e3a18d575d44955453501aa05b0dee98184162c5 /kernel/sched | |
| parent | b4c9c9f15649c98a5b45408919d1ff4fd7f5531c (diff) | |
| download | lwn-8d4d9c7b4333abccb3bf310d76ef7ea2edb9828f.tar.gz lwn-8d4d9c7b4333abccb3bf310d76ef7ea2edb9828f.zip | |
sched/debug: Fix memory corruption caused by multiple small reads of flags
Reading /proc/sys/kernel/sched_domain/cpu*/domain0/flags mutliple times
with small reads causes oopses with slub corruption issues because the kfree is
free'ing an offset from a previous allocation. Fix this by adding in a new
pointer 'buf' for the allocation and kfree and use the temporary pointer tmp
to handle memory copies of the buf offsets.
Fixes: 5b9f8ff7b320 ("sched/debug: Output SD flag names rather than their values")
Reported-by: Jeff Bastian <jbastian@redhat.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20201029151103.373410-1-colin.king@canonical.com
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/debug.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 0655524700d2..2357921580f9 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -251,7 +251,7 @@ static int sd_ctl_doflags(struct ctl_table *table, int write, unsigned long flags = *(unsigned long *)table->data; size_t data_size = 0; size_t len = 0; - char *tmp; + char *tmp, *buf; int idx; if (write) @@ -269,17 +269,17 @@ static int sd_ctl_doflags(struct ctl_table *table, int write, return 0; } - tmp = kcalloc(data_size + 1, sizeof(*tmp), GFP_KERNEL); - if (!tmp) + buf = kcalloc(data_size + 1, sizeof(*buf), GFP_KERNEL); + if (!buf) return -ENOMEM; for_each_set_bit(idx, &flags, __SD_FLAG_CNT) { char *name = sd_flag_debug[idx].name; - len += snprintf(tmp + len, strlen(name) + 2, "%s ", name); + len += snprintf(buf + len, strlen(name) + 2, "%s ", name); } - tmp += *ppos; + tmp = buf + *ppos; len -= *ppos; if (len > *lenp) @@ -294,7 +294,7 @@ static int sd_ctl_doflags(struct ctl_table *table, int write, *lenp = len; *ppos += len; - kfree(tmp); + kfree(buf); return 0; } |