From: Zijun Hu <quic_zijuhu@quicinc.com> mainline inclusion from mainline-v6.11-rc1 commit dd6e9894b451e7c85cceb8e9dc5432679a70e7dc category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAKPXP CVE: CVE-2024-42292 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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> Reviewed-by: Lk Sii <lk_sii@163.com> Link: https://lore.kernel.org/r/1717074877-11352-1-git-send-email-quic_zijuhu@quic... Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Zhao Wenhui <zhaowenhui8@huawei.com> --- 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 b5fc7b9ce197..1af2e79b5c2d 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -430,8 +430,23 @@ 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; -- 2.34.1