diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2019-01-08 18:49:00 +0000 |
|---|---|---|
| committer | Laurent Vivier <laurent@vivier.eu> | 2019-01-10 09:36:41 +0100 |
| commit | 2bd3f8998e1e7dcd9afc29fab252fb9936f9e956 (patch) | |
| tree | 0f16aecf8aa56c0a3824354a81ae62e427c7c5d4 | |
| parent | bd8ed485490e1b0ecac5b39fe654bb83b6b39db6 (diff) | |
linux-user: make pwrite64/pread64(fd, NULL, 0, offset) return 0
Linux returns success if pwrite64() or pread64() are called with a
zero length NULL buffer, but QEMU was returning -TARGET_EFAULT.
This is the same bug that we fixed in commit 58cfa6c2e6eb51b23cc9
for the write syscall, and long before that in 38d840e6790c29f59
for the read syscall.
Fixes: https://bugs.launchpad.net/qemu/+bug/1810433
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20190108184900.9654-1-peter.maydell@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
| -rw-r--r-- | linux-user/syscall.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 29bac79b61..d6605b8b50 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -9716,8 +9716,15 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, arg4 = arg5; arg5 = arg6; } - if (!(p = lock_user(VERIFY_WRITE, arg2, arg3, 0))) - return -TARGET_EFAULT; + if (arg2 == 0 && arg3 == 0) { + /* Special-case NULL buffer and zero length, which should succeed */ + p = 0; + } else { + p = lock_user(VERIFY_WRITE, arg2, arg3, 0); + if (!p) { + return -TARGET_EFAULT; + } + } ret = get_errno(pread64(arg1, p, arg3, target_offset64(arg4, arg5))); unlock_user(p, arg2, ret); return ret; @@ -9726,8 +9733,15 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_long arg1, arg4 = arg5; arg5 = arg6; } - if (!(p = lock_user(VERIFY_READ, arg2, arg3, 1))) - return -TARGET_EFAULT; + if (arg2 == 0 && arg3 == 0) { + /* Special-case NULL buffer and zero length, which should succeed */ + p = 0; + } else { + p = lock_user(VERIFY_READ, arg2, arg3, 1); + if (!p) { + return -TARGET_EFAULT; + } + } ret = get_errno(pwrite64(arg1, p, arg3, target_offset64(arg4, arg5))); unlock_user(p, arg2, 0); return ret; |