[Qemu-devel] [PATCH 2/2] linux-user: fix emulation of /proc/self/maps

[riku . voipio]

From: Alexander Graf <address@hidden>

Improve the emulation of /proc/self/maps by reading the underlying
host maps file and passing lines through with addresses adjusted
to be guest addresses. This is necessary to avoid false triggers
of the glibc check that a format string containing '%n' is not in
writable memory. (For an example see the bug reported in
https://bugs.launchpad.net/qemu-linaro/+bug/947888 where gpg aborts.)

Signed-off-by: Alexander Graf <address@hidden>
Signed-off-by: Peter Maydell <address@hidden>
Signed-off-by: Riku Voipio <address@hidden>
---
 linux-user/syscall.c |   42 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 801b8ed..20d2a74 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4866,13 +4866,53 @@ int get_osversion(void)
 
 static int open_self_maps(void *cpu_env, int fd)
 {
+#if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_UNICORE32)
     TaskState *ts = ((CPUArchState *)cpu_env)->opaque;
+#endif
+    FILE *fp;
+    char *line = NULL;
+    size_t len = 0;
+    ssize_t read;
+
+    fp = fopen("/proc/self/maps", "r");
+    if (fp == NULL) {
+        return -EACCES;
+    }
 
+    while ((read = getline(&line, &len, fp)) != -1) {
+        int fields, dev_maj, dev_min, inode;
+        uint64_t min, max, offset;
+        char flag_r, flag_w, flag_x, flag_p;
+        char path[512] = "";
+        fields = sscanf(line, "%"PRIx64"-%"PRIx64" %c%c%c%c %"PRIx64" %x:%x %d"
+                        " %512s", &min, &max, &flag_r, &flag_w, &flag_x,
+                        &flag_p, &offset, &dev_maj, &dev_min, &inode, path);
+
+        if ((fields < 10) || (fields > 11)) {
+            continue;
+        }
+        if (!strncmp(path, "[stack]", 7)) {
+            continue;
+        }
+        if (h2g_valid(min) && h2g_valid(max)) {
+            dprintf(fd, TARGET_ABI_FMT_lx "-" TARGET_ABI_FMT_lx
+                    " %c%c%c%c %08" PRIx64 " %02x:%02x %d%s%s\n",
+                    h2g(min), h2g(max), flag_r, flag_w,
+                    flag_x, flag_p, offset, dev_maj, dev_min, inode,
+                    path[0] ? "          " : "", path);
+        }
+    }
+
+    free(line);
+    fclose(fp);
+
+#if defined(TARGET_ARM) || defined(TARGET_M68K) || defined(TARGET_UNICORE32)
     dprintf(fd, "%08llx-%08llx rw-p %08llx 00:00 0          [stack]\n",
                 (unsigned long long)ts->info->stack_limit,
                 (unsigned long long)(ts->stack_base + (TARGET_PAGE_SIZE - 1))
                                      & TARGET_PAGE_MASK,
-                (unsigned long long)ts->stack_base);
+                (unsigned long long)0);
+#endif
 
     return 0;
 }
-- 
1.7.9.5