From 1f6a6cc82ed305c09385753c80bb7b3bc9eea864 Mon Sep 17 00:00:00 2001 From: Tang Chen Date: Wed, 6 Aug 2014 16:05:11 -0700 Subject: [PATCH] mem-hotplug: avoid illegal state prefixed with legal state when changing state of memory_block We use the following command to online a memory_block: echo online|online_kernel|online_movable > /sys/devices/system/memory/memoryXXX/state But, if we do the following: echo online_fhsjkghfkd > /sys/devices/system/memory/memoryXXX/state the block will also be onlined. This is because the following code in store_mem_state() does not compare the whole string, but only the prefix of the string. store_mem_state() { ...... 328 if (!strncmp(buf, "online_kernel", min_t(int, count, 13))) Here, only compare the first 13 letters of the string. If we give "online_kernelXXXXXX", it will be recognized as online_kernel, which is incorrect. 329 online_type = ONLINE_KERNEL; 330 else if (!strncmp(buf, "online_movable", min_t(int, count, 14))) We have the same problem here, 331 online_type = ONLINE_MOVABLE; 332 else if (!strncmp(buf, "online", min_t(int, count, 6))) here, (Here is more problematic. If we give online_movalbe, which is a typo of online_movable, it will be recognized as online without noticing the author.) 333 online_type = ONLINE_KEEP; 334 else if (!strncmp(buf, "offline", min_t(int, count, 7))) and here. 335 online_type = -1; 336 else { 337 ret = -EINVAL; 338 goto err; 339 } ...... } This patch fixes this problem by using sysfs_streq() to compare the whole string. Signed-off-by: Tang Chen Reported-by: Hu Tao Cc: Greg Kroah-Hartman Cc: Lai Jiangshan Cc: Yasuaki Ishimatsu Cc: Gu Zheng Acked-by: Toshi Kani Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/base/memory.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/base/memory.c b/drivers/base/memory.c index 89f752d..c6707df 100644 --- a/drivers/base/memory.c +++ b/drivers/base/memory.c @@ -315,13 +315,13 @@ store_mem_state(struct device *dev, if (ret) return ret; - if (!strncmp(buf, "online_kernel", min_t(int, count, 13))) + if (sysfs_streq(buf, "online_kernel")) online_type = ONLINE_KERNEL; - else if (!strncmp(buf, "online_movable", min_t(int, count, 14))) + else if (sysfs_streq(buf, "online_movable")) online_type = ONLINE_MOVABLE; - else if (!strncmp(buf, "online", min_t(int, count, 6))) + else if (sysfs_streq(buf, "online")) online_type = ONLINE_KEEP; - else if (!strncmp(buf, "offline", min_t(int, count, 7))) + else if (sysfs_streq(buf, "offline")) online_type = -1; else { ret = -EINVAL; -- 2.7.4