diff options
| author | LemonBoy <thatlemon@gmail.com> | 2020-04-17 17:34:54 +0200 |
|---|---|---|
| committer | Laurent Vivier <laurent@vivier.eu> | 2020-11-11 11:01:08 +0100 |
| commit | c7811022ebfcaae64e06383ff734f3b3651bf892 (patch) | |
| tree | 223144ac5f8d4fc8cac3b114f55b10d7d5505165 | |
| parent | ce437484fced8292d90497d7b740335428fffed6 (diff) | |
linux-user: Prevent crash in epoll_ctl
From 894bb5172705e46a3a04c93b4962c0f0cafee814 Mon Sep 17 00:00:00 2001
From: Giuseppe Musacchio <thatlemon@gmail.com>
Date: Fri, 17 Apr 2020 17:25:07 +0200
Subject: [PATCH] linux-user: Prevent crash in epoll_ctl
The `event` parameter is ignored by the kernel if `op` is EPOLL_CTL_DEL,
do the same and avoid returning EFAULT if garbage is passed instead of a
valid pointer.
Signed-off-by: Giuseppe Musacchio <thatlemon@gmail.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <a244fa67-dace-abdb-995a-3198bd80fee8@gmail.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
| -rw-r--r-- | linux-user/syscall.c | 26 |
1 files changed, 17 insertions, 9 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 3160a9ba06..27adee908e 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -12590,17 +12590,25 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, struct epoll_event ep; struct epoll_event *epp = 0; if (arg4) { - struct target_epoll_event *target_ep; - if (!lock_user_struct(VERIFY_READ, target_ep, arg4, 1)) { - return -TARGET_EFAULT; + if (arg2 != EPOLL_CTL_DEL) { + struct target_epoll_event *target_ep; + if (!lock_user_struct(VERIFY_READ, target_ep, arg4, 1)) { + return -TARGET_EFAULT; + } + ep.events = tswap32(target_ep->events); + /* + * The epoll_data_t union is just opaque data to the kernel, + * so we transfer all 64 bits across and need not worry what + * actual data type it is. + */ + ep.data.u64 = tswap64(target_ep->data.u64); + unlock_user_struct(target_ep, arg4, 0); } - ep.events = tswap32(target_ep->events); - /* The epoll_data_t union is just opaque data to the kernel, - * so we transfer all 64 bits across and need not worry what - * actual data type it is. + /* + * before kernel 2.6.9, EPOLL_CTL_DEL operation required a + * non-null pointer, even though this argument is ignored. + * */ - ep.data.u64 = tswap64(target_ep->data.u64); - unlock_user_struct(target_ep, arg4, 0); epp = &ep; } return get_errno(epoll_ctl(arg1, arg2, arg3, epp)); |