From 9c1da8b5ee7f6e80e6b683e7fb73df1029a7cbbe Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Fri, 24 Feb 2023 01:39:06 +0100 Subject: linux-user: Fix unaligned memory access in prlimit64 syscall MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit target_rlimit64 contains uint64_t fields, so it's 8-byte aligned on some hosts, while some guests may align their respective type on a 4-byte boundary. This may lead to an unaligned access, which is an UB. Fix by defining the fields as abi_ullong. This makes the host alignment match that of the guest, and lets the compiler know that it should emit code that can deal with the guest alignment. While at it, also use __get_user() and __put_user() instead of tswap64(). Fixes: 163a05a8398b ("linux-user: Implement prlimit64 syscall") Reported-by: Richard Henderson Signed-off-by: Ilya Leoshkevich Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Laurent Vivier Message-Id: <20230224003907.263914-2-iii@linux.ibm.com> Signed-off-by: Laurent Vivier --- linux-user/generic/target_resource.h | 4 ++-- linux-user/syscall.c | 8 ++++---- 2 files changed, 6 insertions(+), 6 deletions(-) (limited to 'linux-user') diff --git a/linux-user/generic/target_resource.h b/linux-user/generic/target_resource.h index 539d8c4..37d3eb0 100644 --- a/linux-user/generic/target_resource.h +++ b/linux-user/generic/target_resource.h @@ -12,8 +12,8 @@ struct target_rlimit { }; struct target_rlimit64 { - uint64_t rlim_cur; - uint64_t rlim_max; + abi_ullong rlim_cur; + abi_ullong rlim_max; }; #define TARGET_RLIM_INFINITY ((abi_ulong)-1) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 64b71b1..69cc4b6 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -12876,8 +12876,8 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1, if (!lock_user_struct(VERIFY_READ, target_rnew, arg3, 1)) { return -TARGET_EFAULT; } - rnew.rlim_cur = tswap64(target_rnew->rlim_cur); - rnew.rlim_max = tswap64(target_rnew->rlim_max); + __get_user(rnew.rlim_cur, &target_rnew->rlim_cur); + __get_user(rnew.rlim_max, &target_rnew->rlim_max); unlock_user_struct(target_rnew, arg3, 0); rnewp = &rnew; } @@ -12887,8 +12887,8 @@ static abi_long do_syscall1(CPUArchState *cpu_env, int num, abi_long arg1, if (!lock_user_struct(VERIFY_WRITE, target_rold, arg4, 1)) { return -TARGET_EFAULT; } - target_rold->rlim_cur = tswap64(rold.rlim_cur); - target_rold->rlim_max = tswap64(rold.rlim_max); + __put_user(rold.rlim_cur, &target_rold->rlim_cur); + __put_user(rold.rlim_max, &target_rold->rlim_max); unlock_user_struct(target_rold, arg4, 1); } return ret; -- cgit v1.1