[PATCH 0/2] linux-user: two fixes to coredump generation

[PATCH 0/2] linux-user: two fixes to coredump generation

[Thomas Weißschuh]

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
Thomas Weißschuh (2):
      linux-user/elfload: test return value of getrlimit
      linux-user/elfload: check PR_GET_DUMPABLE before creating coredump

 linux-user/elfload.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)
---
base-commit: 9c673a41eefc50f1cb2fe3c083e7de842c7d276a
change-id: 20231115-qemu-user-dumpable-d499c0396103

Best regards,
-- 
Thomas Weißschuh <thomas@t-8ch.de>

[PATCH 1/2] linux-user/elfload: test return value of getrlimit

[Thomas Weißschuh]

Should getrlimit() fail the value of dumpsize.rlimit_cur may not be
initialized. Avoid reading garbage data by checking the return value of
getrlimit.

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
 linux-user/elfload.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 4cd6891d7b6a..799fe8497346 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -4667,8 +4667,7 @@ static int elf_core_dump(int signr, const CPUArchState *env)
     init_note_info(&info);
 
     errno = 0;
-    getrlimit(RLIMIT_CORE, &dumpsize);
-    if (dumpsize.rlim_cur == 0)
+    if (getrlimit(RLIMIT_CORE, &dumpsize) == 0 && dumpsize.rlim_cur == 0)
         return 0;
 
     corefile = core_dump_filename(ts);

-- 
2.42.1

[PATCH 2/2] linux-user/elfload: check PR_GET_DUMPABLE before creating coredump

[Thomas Weißschuh]

A process can opt-out of coredump creation by calling
prctl(PR_SET_DUMPABLE, 0).
linux-user passes this call from the guest through to the
operating system.
From there it can be read back again to avoid creating coredumps from
qemu-user itself if the guest chose so.

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
 linux-user/elfload.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 799fe8497346..76d5740af0ca 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2,6 +2,7 @@
 #include "qemu/osdep.h"
 #include <sys/param.h>
 
+#include <sys/prctl.h>
 #include <sys/resource.h>
 #include <sys/shm.h>
 
@@ -4667,6 +4668,10 @@ static int elf_core_dump(int signr, const CPUArchState *env)
     init_note_info(&info);
 
     errno = 0;
+
+    if (prctl(PR_GET_DUMPABLE) == 0)
+        return 0;
+
     if (getrlimit(RLIMIT_CORE, &dumpsize) == 0 && dumpsize.rlim_cur == 0)
         return 0;
 

-- 
2.42.1