see
linux commit 1446e1df9eb183fdf81c3f0715402f1d7595d4cb
kernel: Implement selective syscall userspace redirection
linux commit 36a6c843fd0d8e02506681577e96dabd203dd8e8
entry: Use different define for selector variable in SUD
redirect syscalls to a userspace handler via SIGSYS, except for a specific
range of code. can be toggled via a memory write to a selector variable.
mainly for wine.
see
linux commit b0a0c2615f6f199a656ed8549d7dce625d77aa77
epoll: wire up syscall epoll_pwait2
linux commit 58169a52ebc9a733aeb5bea857bc5daa71a301bb
epoll: add syscall epoll_pwait2
epoll_wait with struct timespec timeout instead of int. no time32 variant.
This reduces entropy of the canary from 64-bit to 56-bit in exchange
for mitigating non-terminated C string overflows by setting the second
byte of the canary to nul, so that off-by-one write overflow with a
nul byte can still be detected.
Idea from GrapheneOS bionic commit 7024d880b51f03a796ff8832f1298f2f1531fd7b
gcc-12 with -frounding-mode will do inexact constant conversions at
runtime according to the runtime rounding mode.
in the math library we want constants to be rounding mode independent
so this patch fixes cases where new runtime conversions happen with
gcc-12.
fortunately this only affects two minor cases, the fix uses global
initializers where rounding mode does not apply.
after the patch the same amount of conversions happen with gcc-12 as
with gcc-11.
commit a90d9da1d1 made fgetws look for
changes to errno by fgetwc to detect encoding errors, since ISO C did
not allow the implementation to set the stream's error flag in this
case, and the fgetwc interface did not admit any other way to detect
the error. however, the possibility of fgetwc setting errno to EILSEQ
in the success path was overlooked, and in fact this can happen if the
buffer ends with a partial character, causing mbtowc to be called with
only part of the character available.
since that change was made, the C standard was amended to specify that
fgetwc set the stream error flag on encoding errors, and commit
511d70738b made it do so. thus, there is
no longer any need for fgetws to poke at errno to handle encoding
errors.
this commit reverts commit a90d9da1d1
and thereby fixes the problem.
this bug goes back to commit 1cc81f5cb0
where zoneinfo file support was first added. in scan_trans, which
searches for the appropriate local time/dst rule in effect at a given
time, times prior to the second transition time caused the -1 slot of
the index to be read to determine the previous rule in effect. this
memory was always valid (part of another zoneinfo table in the mapped
file) but the byte value read was then used to index another table,
possibly going outside the bounds of the mmap. most of the time, the
result was limited to misinterpretation of the rule in effect at that
time (pre-1900s), but it could produce a crash if adjacent memory was
not readable.
the root cause of the problem, however, was that the logic for this
code path was all wrong. as documented in the comment, times before
the first transition should be treated as using the lowest-numbered
non-dst rule, or rule 0 if no non-dst rules exist. if the argument is
in units of local time, however, the rule prior to the first
transition is needed to determine if it falls before or after it, and
that's where the -1 index was wrongly used.
instead, use the documented logic to find out what rule would be in
effect before the first transition, and apply it as the offset if the
argument was given in local time.
the new code has not been heavily tested, but no longer performs
potentially out-of-bounds accesses, and successfully handles the 1883
transition from local mean time to central standard time in the test
case the error was reported for.
these are specified to use the sign of the imaginary part of the input
as the sign of zero in the result, but wrongly copied the sign of the
real part.
this is a POSIX requirement. we previously relied on the underlying fd
(or other backend) seek operation to produce the error, but since
linux lseek now supports other seek modes (SEEK_DATA and SEEK_HOLE)
which do not interact well with stdio buffering, this is insufficient.
instead, explicitly check whence before performing any operations.
these are linux specific constants. glibc exposes them behind
_GNU_SOURCE, but, since SEEK_* is reserved for the implementation, we
can simply define them. furthermore, since they can't be used with
fseek() and other functions that deal with FILE, we don't add them to
stdio.h.
these characters combine onto a base character (initial) and therefore
need to have width 0. the original binary-search implementation of
wcwidth handled them correctly, but a regression was introduced in
commit 1b0ce9af6d by generating the new
tables from unicode without noticing that the classification logic in
use (unicode character category Mn/Me/Cf) was insufficient to catch
these characters.
strtod_l, strtof_l, and strtold_l originally existed only as
glibc-ABI-compat symbols. as noted in the commit which added them,
17a60f9d32, making them aliases for the
non-_l functions was a hack and not appropriate if they ever became
public API.
unfortunately, commit 35eb1a1a9b did
make them public without undoing the hack. fix that now by moving the
the _l functions to their own file as wrappers that just throw away
the locale_t argument.
commit 7be59733d7 introduced the
hwcap-based branches to support the SPE FPU, but wrongly coded them as
bitwise tests on the computed address of __hwcap, not a value loaded
from that address. replace the add with indexed load to fix it.
the snd_pcm_mmap_control struct used with SNDRV_PCM_IOCTL_SYNC_PTR was
mistakenly defined in the kernel uapi with "before u32" padding both
before and after the first u32 member. our conversion between the
modern struct and the legacy time32 struct was written without
awareness of that mistake, and assumed the time64 version of the
struct was the intended form with padding to match the layout on
64-bit archs. as a result, the struct was not converted correctly when
running on old kernels, with audio glitches as the likely result.
this was discovered thanks to a related bug in the kernel, whereby
32-bit userspace running on a 64-bit kernel also suffered from the
types mismatching. the mistaken layout is now the ABI and can't be
changed -- or at least making a new ioctl to change it would just
result in a worse situation.
our conversion here is changed to treat the snd_pcm_mmap_control
substruct as two separate substructs at locations dependent on
endianness (since the displacement depends on endianness), using the
existing conversion framework.
we make qsort a wrapper by providing a wrapper_cmp function that uses
the extra argument as a function pointer. should be optimized to a tail
call on most architectures, as long as it's built with
-fomit-frame-pointer, so the performance impact should be minimal.
to keep the git history clean, for now qsort_r is implemented in qsort.c
and qsort is implemented in qsort_nr.c. qsort.c also received a few
trivial cleanups, including replacing (*cmp)() calls with cmp().
qsort_nr.c contains only wrapper_cmp and qsort as a qsort_r wrapper
itself.
When the soft-float ABI for PowerPC was added in commit
5a92dd95c7, with Freescale cpus using
the alternative SPE FPU as the main use case, it was noted that we
could probably support hard float on them, but that it would involve
determining some difficult ABI constraints. This commit is the
completion of that work.
The Power-Arch-32 ABI supplement defines the ABI profiles, and indeed
ATR-SPE is built on ATR-SOFT-FLOAT. But setjmp/longjmp compatibility
are problematic for the same reason they're problematic on ARM, where
optional float-related parts of the register file are "call-saved if
present". This requires testing __hwcap, which is now done.
In keeping with the existing powerpc-sf subarch definition, which did
not have fenv, the fenv macros are not defined for SPE and the SPEFSCR
control register is left (and assumed to start in) the default mode.
both passing a null pointer to memcpy with length 0, and adding 0 to a
null pointer, are undefined. in some sense this is 'benign' UB, but
having it precludes use of tooling that strictly traps on UB. there
may be better ways to fix it, but conditioning the operations which
are intended to be no-ops in the k==0 case on k being nonzero is a
simple and safe solution.
commit 6d99ad91e8 introduced this
regression as part of a larger change, based on an incorrect
assumption that rdhwr being part of the mips r2 ISA level meant that
the TLS register, known in the mips documentation as UserLocal, was
unconditionally present on chips providing this ISA level and would
not need trap-and-emulate. this turns out to be false.
based on research by Stanislav Kljuhhin and Abilio Marques, who
reported the problem as a performance regression on certain routers
using OpenWRT vs older uclibc-based versions, it turns out the mips
manuals document the UserLocal register as a feature that might or
might not be implemented or enabled, reflected by a cpu capability bit
in the CONFIG3 register, and that Linux checks for this and has to
explicitly enable it on models that have it.
thus, it's indeed possible that r2+ chips can lack the feature,
bringing us back to the situation where Linux only has a fast
trap-and-emulate path for the case where the destination register is
$3. so, always read the thread pointer through $3. this may incur a
gratuitous move to the desired final register on chips where it's not
needed, but it really doesn't matter.
len is unsigned and can never be smaller than 0. though unlikely, an
error in read() would have lead to an out of bounds write to name.
Reported-by: Michael Forney <mforney@mforney.org>
due to historical reasons, the mips signal set has 128 bits rather
than 64 like on every other arch. this was special-cased correctly, at
least for 32-bit mips, at one time, but was inadvertently broken in
commit 7c440977db, and seems never to
have been right on mips64/n32.
as consequenct of this bug, applications making use of high realtime
signal numbers on mips may have been able to execute application code
in contexts where doing so was unsafe.
the kernel structure has padding of the shm_segsz member up to 64
bits, as well as 2 unused longs at the end. somehow that was
overlooked when the powerpc port was added, and it has been broken
ever since; applications compiled with the wrong definition do not
correctly see the shm_segsz, shm_cpid, and shm_lpid members.
fixing the definition just by adding the missing padding would break
the ABI size of the structure as well as the position of the time64
shm_atime and shm_dtime members we added at the end. instead, just
move one of the unused padding members from the original end (before
time64) of the structure to the position of the missing padding. this
preserves size and preserves correct behavior of any compiled code
that was already working. programs affected by the wrong definition
need to be recompiled with the correct one.
previously, the contents of the TZ variable were considered a
candidate for a file/path name only if they began with a colon or
contained a slash before any comma. the latter was very sloppy logic
to avoid treating any valid POSIX TZ string as a file name, but it
also triggered on values that are not valid POSIX TZ strings,
including 3-letter timezone names without any offset.
instead, only treat the TZ variable as POSIX form if it begins with a
nonzero standard time name followed by +, -, or a digit.
also, special case GMT and UTC to always be treated as POSIX form
(with implicit zero offset) so that a stray file by the same name
cannot break software that depends on setting TZ=GMT or TZ=UTC.
POSIX places an obscure requirement on popen which is like a limited
version of close-on-exec:
"The popen() function shall ensure that any streams from previous
popen() calls that remain open in the parent process are closed in
the new child process."
if the POSIX-future 'e' mode flag is passed, producing a pipe FILE
with FD_CLOEXEC on the underlying pipe, this requirement is
automatically satisfied. however, for applications which use multiple
concurrent popen pipes but don't request close-on-exec, fd leaks from
earlier popen calls to later ones could produce deadlock situations
where processes are waiting for a pipe EOF that will never happen.
to fix this, iterate through all open FILEs and add close actions for
those obtained from popen. this requires holding a lock on the open
file list across the posix_spawn call so that additional popen FILEs
are not created after the list is traversed. note that it's still
possible for another popen call to start and create its pipe while the
lock is held, but such pipes are created with O_CLOEXEC and only drop
close-on-exec status (when 'e' flag is omitted) under control of the
lock.
the newly allocated FILE * has not yet leaked to the application and
is only visible to stdio internals until popen returns. since we do
not change any fields of the structure observed by libc internals,
only the pipe_pid member, locking is not necessary.
__tls_get_addr should not be called with an invalid TLS module id of
0. in practice it probably "works", returning the DTV length as if it
were a pointer, and the callback should probably not inspect
dlpi_tls_data in this case, but it's likely that some real-world
callbacks use a check on dlpi_tls_data being non-null, rather than on
dlpi_tls_modid being nonzero, to conclude that the module has TLS.
With mallocng, calling posix_memalign() or aligned_alloc() will
SIGSEGV if the internal malloc() call returns NULL. This does not
occur with oldmalloc, which explicitly checks for allocation failure.
this is a Linux-specific function and not covered by POSIX's
requirements for which interfaces are cancellation points, but glibc
makes it one and existing software relies on it being one.
at some point a review for similar functions that should be made
cancellation points should be done.
dl_iterate_phdr was wrongly reporting the address of the DSO's PT_TLS
image rather than the calling thread's instance of the TLS. the man
page, which is essentially normative for a nonstandard function of
this sort, clearly specifies the latter. it does not clarify where
exactly within/relative-to the image the pointer should point, but the
reasonable thing to do is match the ABI's DTP offset, and this seems
to be what other implementations do.
popen was special-casing the possibility (only possible when the
parent closed stdin and/or stdout) that the child's end of the pipe
was already on the final desired fd number, in which case there was no
way to get rid of its close-on-exec flag in the child. commit
6fc6ca1a32 made this unnecessary by
implementing the POSIX-future requirement that dup2 file actions with
equal source and destination fd values remove the close-on-exec flag.
this makes it possible to perform actions on file actions objects with
a libc-internal lock held without creating lock order relationships
that are silently imposed on an application-provided malloc.
reportedly the GNU linker can emit such segments, causing spurious
failure to load due to mmap with a length of zero producing EINVAL.
no action is required for such a load map (it's effectively a nop in
the program headers table) so just treat it as always successful.
since 4.1, gcc has had the __returns_twice__ attribute and has
required functions which return twice to carry it; however it's always
applied it automatically to known setjmp-like function names. clang
however does not do this reliably, at least not with -ffreestanding
and possibly under other conditions, resulting in silent emission of
wrong code.
since the symbol name setjmp is in no way special (setjmp is specified
as a macro that could expand to use any implementation-specific symbol
name or names), a compiler is justified not to do anything special
without further hints, and it's reasonable to do what we can to
provide such hints.
gcc 4.0.x and earlier do not recognize the attribute, so make use
conditional on __GNUC__ macros. clang and other gcc-like compilers
report (and have always reported) a later "GNUC" version so the
preprocessor conditional should function as desired for them as too.
undefine the internal macro after use so that nothing abuses it as a
public feature.
add synchronouse and asynchronous tag check failure codes, see
linux commit 74f1082487feb90bbf880af14beb8e29c3030c9f
arm64: mte: Add specific SIGSEGV codes
Szabolcs Nagy
Alexey Kodanev
jvoisin
Rich Felker
pelco
Érico Nogueira
Wesley Wiser
Ismael Luceno
Khem Raj
Michael Forney
Joakim Sindholt
Dominic Chen