From: Ilya Leoshkevich <iii@linux.ibm.com>
Date: Mon, 14 Oct 2024 20:34:21 +0000 (+0200)
Subject: linux-user: Emulate /proc/self/maps under mmap_lock
X-Git-Tag: v8.2.8~38
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=dad762774e9ac5a19f3e2d3875cdd63f529dcf03;p=thirdparty%2Fqemu.git

linux-user: Emulate /proc/self/maps under mmap_lock

If one thread modifies the mappings and another thread prints them,
a situation may occur that the printer thread sees a guest mapping
without a corresponding host mapping, leading to a crash in
open_self_maps_2().

Cc: qemu-stable@nongnu.org
Fixes: 7b7a3366e142 ("linux-user: Use walk_memory_regions for open_self_maps")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20241014203441.387560-1-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit bbd5630a75e70a0f1bcf04de74c94aa94a145628)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: context fix in linux-user/syscall.c due to missing v9.0.0-421-g59272469bd13
 "user: Use get_task_state() helper")
---

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index d9212aa9661..e1783660931 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8120,17 +8120,19 @@ static int open_self_maps_1(CPUArchState *env, int fd, bool smaps)
 {
     struct open_self_maps_data d = {
         .ts = env_cpu(env)->opaque,
-        .host_maps = read_self_maps(),
         .fd = fd,
         .smaps = smaps
     };
 
+    mmap_lock();
+    d.host_maps = read_self_maps();
     if (d.host_maps) {
         walk_memory_regions(&d, open_self_maps_2);
         free_self_maps(d.host_maps);
     } else {
         walk_memory_regions(&d, open_self_maps_3);
     }
+    mmap_unlock();
     return 0;
 }