Date: Thu, 31 Oct 2019 02:48:32 +0100 From: Szabolcs Nagy <nsz@...t70.net> To: musl@...ts.openwall.com Subject: Re: libc-test regression/syscall-sign-extend.c * Rich Felker <dalias@...c.org> [2019-08-15 12:08:13 -0400]: > libc-test has one test regression/syscall-sign-extend.c whose purpose > is testing an x32 bug whereby pointers passed to syscall() got > sign-extended, fixed by 5f95f965e933c5b155db75520ac27c92ddbcf400 > (albeit with a nasty hack). > > However it's using SYS_clock_gettime as the test, which means it will > break on 32-bit archs when time_t changes to 64-bit and the old > syscall no longer matches the libc ABI types. > > (It also doesn't seem to be doing anything to ensure that the pointer > is "negative" in a sign-extension case; it just assumes the stack is > at the top of memory. But this probably doesn't matter in practice.) > > I think we should find a different syscall to test that's immune to > kernel/libc disagreements over types or macro values. The simplest > example might be SYS_read - opening a pipe, writing a byte to it with > write(), and confirming that syscall(SYS_read, ...) reads it back. ok changed the test to use SYS_read. thanks. > > Alternatively clock_gettime could be tested just to modify the > pointed-to memory (e.g. by pre-filling it with 0xff) without assuming > it matches struct timespec layout, but that also assumes the CLOCK_* > macros map directly to syscall API. > > Rich
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.