hulk inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9REGZ CVE: NA

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The following c language code can trigger KASAN's global variable out-of-bounds access error in kobject_action_type():

int main() { int fd; char *filename = "/sys/block/ram12/uevent"; char str[86] = "offline"; int len = 86;

fd = open(filename, O_WRONLY); if (fd == -1) { printf("open"); exit(1); }

if (write(fd, str, len) == -1) { printf("write"); exit(1); }

close(fd); return 0; }

Function kobject_action_type() receives the input parameters buf and count, where count is the length of the string buf.

In the use case we provided, count is 86, the count_first is 85. Buf points to a string with a length of 86, and its first seven characters are "offline". In line 87 of the code, kobject_actions[action] is the string "offline" with the length of 7,an out-of-boundary access will appear:

kobject_actions[action][85].

Modify the judgment logic in line 87. If the length of the string kobject_actions[action] is greater than count_first(e.g. buf is "off", count is 3), continue the loop. Otherwise, the match is considered successful.

This change means that our test case will be successfully parsed as an offline event and no out-of-bounds access error will occur.

Fixes: f36776fafbaa ("kobject: support passing in variables for synthetic uevents") Signed-off-by: Xia Fukun xiafukun@huawei.com --- lib/kobject_uevent.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index c87d5b6a8a55..8056def4c028 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -84,7 +84,7 @@ static int kobject_action_type(const char *buf, size_t count, for (action = 0; action < ARRAY_SIZE(kobject_actions); action++) { if (strncmp(kobject_actions[action], buf, count_first) != 0) continue; - if (kobject_actions[action][count_first] != '\0') + if (strlen(kobject_actions[action]) > count_first) continue; if (args) *args = args_start;