Commit fe203ffbb2bd7f93a86013d341aa767a406150bc
2025-03-27T01:31:49
Fix bugs in the x86-64 and x32 target (#887) (#889) This commit fixes two bugs in ffi in the x86-64 target. The bugs were introduced by the commit d21881f55ed4a44d464c9091871e69b0bb47611a ("Fix x86/ffi64 calls with 6 gp and some sse registers"). The first bug is that when we pass an argument with less than 8 bytes, ffi will read memory beyond argument end, causing a crash if the argument is located just before the end of the mapped region. The second bug is in the x32 ABI - pointers in x32 are 4-byte, but GCC assumes that the pointer values in the registers are zero-extended. ffi doesn't respect this assumption, causing crashes in the called library. For example, when we compile this function for x32: int fn(int *a) { if (a) return *a; return -1; } we get this code: fn: testq %rdi, %rdi je .L3 movl (%edi), %eax ret .L3: movl $-1, %eax ret When we call this function using ffi with the argument NULL, the function crashes because top 4 bytes of the RDI register are not cleared. Fixes: d21881f55ed4 ("Fix x86/ffi64 calls with 6 gp and some sse registers (#848)") Signed-off-by: Mikulas Patocka <mikulas@twibright.com>