From 9fea273c8511dd6e34138d028db774b031c0f70c Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Thu, 11 Aug 2016 18:59:39 +0100 Subject: [PATCH] linux-user: Fix llseek with high bit of offset_low set The llseek syscall takes two 32-bit arguments, offset_high and offset_low, which must be combined to form a single 64-bit offset. Unfortunately we were combining them with (uint64_t)arg2 << 32) | arg3 and arg3 is a signed type; this meant that when promoting arg3 to a 64-bit type it would be sign-extended. The effect was that if the offset happened to have bit 31 set then this bit would get sign-extended into all of bits 63..32. Explicitly cast arg3 to abi_ulong to avoid the erroneous sign extension. Reported-by: Chanho Park Signed-off-by: Peter Maydell Tested-by: Chanho Park Message-id: 1470938379-1133-1-git-send-email-peter.maydell@linaro.org --- linux-user/syscall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 7edfe4a228..9facf7c345 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -9389,7 +9389,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, { int64_t res; #if !defined(__NR_llseek) - res = lseek(arg1, ((uint64_t)arg2 << 32) | arg3, arg5); + res = lseek(arg1, ((uint64_t)arg2 << 32) | (abi_ulong)arg3, arg5); if (res == -1) { ret = get_errno(res); } else {