src/lib/libc/stdlib, branch release/13.1.0

qsort.c: prevent undefined behavior

2022-03-04T19:47:02Z

Mark Milliard has detected a case of undefined behavior with the LLVM UBSAN. The mandoc program called qsort with a==NULL and n==0, which is allowed by the POSIX standard. The qsort() in FreeBSD did not attempt to perform any accesses using the passed pointer for n==0, but it did add an offset to the pointer value, which is undefined behavior in case of a NULL pointer. This operation has no adverse effects on any achitecture supported by FreeBSD, but could be caught in more strict environments. After some discussion in the freebsd-current mail list, it was concluded that the case of a==NULL and n!=0 should still be caught by UBSAN (or cause a program abort due to an illegal access) in order to not hide errors in programs incorrectly invoking qsort(). Only the the case of a==NULL and n==0 should be fixed to not perform the undefined operation on a NULL pointer. This commit makes qsort() exit before reaching the point of potentially undefined behvior for the case n==0, but does not test the value of a, since the result will not depend on whether this pointer is NULL or an actual pointer to an array if n==0. The issue found by Mark Milliard in the whatis command has been reported to the upstream (OpenBSD) and has already been patched there. (cherry picked from commit d106f982a54cd299671ccad58bc456138a22ae7b)

Fix null pointer subtraction in mergesort()

2021-08-31T19:05:43Z

Clang 13 produces the following warning for this function: lib/libc/stdlib/merge.c:137:41: error: performing pointer subtraction with a null pointer has undefined behavior [-Werror,-Wnull-pointer-subtraction] if (!(size % ISIZE) && !(((char *)base - (char *)0) % ISIZE)) ^ ~~~~~~~~~ This is meant to check whether the size and base parameters are aligned to the size of an int, so use our __is_aligned() macro instead. Also remove the comment that indicated this "stupid subtraction" was done to pacify some ancient and unknown Cray compiler, and which has been there since the BSD 4.4 Lite Lib Sources were imported. (cherry picked from commit 4e5d32a445f90d37966cd6de571978551654e3f3)

Fix race between first rand(3) calls with _once().

2021-08-19T01:11:51Z

Before this patch there was a chance for thread that called rand(3) slightly later to see rand3_state already allocated, but not yet initialized. While this API is not expected to be thread-safe, it is not expected to crash. ztest on 64-thread system reproduced it reliably for me. Submitted by: avg@ MFC after: 1 month (cherry picked from commit 3a57f08b5042f15bb8ffb2fcce99d082d225d4cf)

_Exit(3): document implementation

2021-08-12T12:37:54Z

(cherry picked from commit ee62fb2e1e14eab35d4e4e92535bcac9fc91eeb8)

libc/qsort: Don't allow interposing recursive calls

2021-03-17T09:46:58Z

This causes problems when using ASAN with a runtime older than 12.0 since the intercept does not expect qsort() to call itself using an interposable function call. This results in infinite recursion and stack exhaustion when a binary compiled with -fsanitize=address calls qsort. See also https://bugs.llvm.org/show_bug.cgi?id=46832 and https://reviews.llvm.org/D84509 (ASAN runtime patch). To prevent this problem, this patch uses a static helper function for the actual qsort() implementation. This prevents interposition and allows for direct calls. As a nice side-effect, we can also move the qsort_s checks to the top-level function and out of the recursive calls. Reviewed By: kib Differential Revision: https://reviews.freebsd.org/D28133 (cherry picked from commit cbcfe28f9d5f975f97b7fb4a0d72bc9780eb0c46)

libc: Fix null pointer arithmetic warning in mergesort

2021-01-20T09:56:01Z

This file has other questionable code and "optimizations" (such as copying one int at a time) that are probably no longer useful, so it might make sense to replace it with a different implementation at some point. Reviewed By: jhb Differential Revision: https://reviews.freebsd.org/D28134

getopt: Fix conversion from string-literal to non-const char *

2021-01-19T21:23:25Z

Define a non-const static char EMSG[] = "" to avoid having to add __DECONST() to all uses of EMSG. Also make current_dash a const char * to fix this warning.

libc: Fix most issues reported by mandoc

2020-12-19T14:54:28Z

- varios "new sentence, new line" warnings - varios "sections out of conventional order" warnings - varios "unusual Xr order" warnings - varios "missing section argument" warnings - varios "no blank before trailing delimiter" warnings - varios "normalizing date format" warnings MFC after: 1 month

Further refinements of ptsname_r(3) interface:

2020-10-20T01:29:45Z

- Hide ptsname_r under __BSD_VISIBLE for now as the specification is not finalized at this time. - Keep Symbol.map sorted. - Avoid the interposing of ptsname_r(3) from an user application from breaking ptsname(3) by making the implementation a static method and call the static function from ptsname(3) instead. Reported by: kib Reviewed by: kib, jilles MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D26845

Implement ptsname_r.

2020-10-17T04:14:38Z

MFC after: 2 weeks PR: 250062 Reviewed by: jilles, 0mp, Ray Differential Revision: https://reviews.freebsd.org/D26647