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[PULL,20/24] linux-user: Emulate /proc/self/maps under mmap_lock

Message ID 20241023033432.1353830-21-richard.henderson@linaro.org
State Accepted
Commit bbd5630a75e70a0f1bcf04de74c94aa94a145628
Headers show
Series [PULL,01/24] tcg: Reset data_gen_ptr correctly | expand

Commit Message

Richard Henderson Oct. 23, 2024, 3:34 a.m. UTC 
From: Ilya Leoshkevich <iii@linux.ibm.com>

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>
---
 linux-user/syscall.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 1354e75694..dd2ec0712b 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8151,17 +8151,19 @@  static int open_self_maps_1(CPUArchState *env, int fd, bool smaps)
 {
     struct open_self_maps_data d = {
         .ts = get_task_state(env_cpu(env)),
-        .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;
 }