On 2024/5/30 21:14, Zijun Hu wrote:
zap_modalias_env() wrongly calculates size of memory block to move, so will cause OOB memory access issue if variable MODALIAS is not the last one within its @env parameter, fixed by correcting size to memmove.
Fixes: 9b3fa47d4a76 ("kobject: fix suppressing modalias in uevents delivered over netlink") Cc: stable@vger.kernel.org Signed-off-by: Zijun Hu quic_zijuhu@quicinc.com
V3: Correct inline comments and take Dmitry's suggestion V2: Correct commit messages and add inline comments
Previous discussion links: https://lore.kernel.org/lkml/ZlYo20ztfLWPyy5d@google.com/ https://lore.kernel.org/lkml/0b916393-eb39-4467-9c99-ac1bc9746512@quicinc.co...
lib/kobject_uevent.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index 03b427e2707e..b7f2fa08d9c8 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -433,8 +433,23 @@ static void zap_modalias_env(struct kobj_uevent_env *env) len = strlen(env->envp[i]) + 1; if (i != env->envp_idx - 1) {
/* @env->envp[] contains pointers to @env->buf[]* with @env->buflen chars, and we are removing* variable MODALIAS here pointed by @env->envp[i]* with length @len as shown below:** 0 @env->buf[] @env->buflen* ---------------------------------------------* ^ ^ ^ ^* | |-> @len <-| target block |* @env->envp[0] @env->envp[i] @env->envp[i + 1]** so the "target block" indicated above is moved* backward by @len, and its right size is* @env->buflen - (@env->envp[i + 1] - @env->envp[0]).*/ memmove(env->envp[i], env->envp[i + 1],
env->buflen - len);
env->buflen - (env->envp[i + 1] - env->envp[0]));for (j = i; j < env->envp_idx - 1; j++) env->envp[j] = env->envp[j + 1] - len;
Reviewed-by: Lk Sii lk_sii@163.com