After the commit 7a4ee86161,
sd_journal_next() following sd_journal_seek_tail() takes no-op,
and we need to call sd_journal_previous(). This may be useful in
some cases, e.g. to fix the issue explained in the previous commit.
When closing the FILE handle attached to a memstream, it may attempt to
do a realloc() that may fail during OOM situations, in which case we are
left with the buffer pointer pointing to NULL and buffer size > 0. For
example:
```
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
void *realloc(void *ptr, size_t size) {
return NULL;
}
int main(int argc, char *argv[])
{
FILE *f;
char *buf;
size_t sz = 0;
f = open_memstream(&buf, &sz);
if (!f)
return -ENOMEM;
fputs("Hello", f);
fflush(f);
printf("buf: 0x%lx, sz: %lu, errno: %d\n",
(unsigned long) buf, sz, errno);
fclose(f);
printf("buf: 0x%lx, sz: %lu, errno: %d\n",
(unsigned long) buf, sz, errno);
return 0;
}
```
```
$ gcc -o main main.c
$ ./main
buf: 0x74d4a0, sz: 5, errno: 0
buf: 0x0, sz: 5, errno: 0
```
This might do unexpected things if the underlying code expects a valid
pointer to the memstream buffer after closing the handle.
Found by Nallocfuzz.
If we fail to combine the new entry with a previous one, or update it in
the hashmap, we might later on attempt a double-free:
=================================================================
==10==ERROR: AddressSanitizer: attempting double-free on 0x611000039fc0 in thread T0:
SCARINESS: 42 (double-free)
#0 0x4a0962 in __interceptor_free /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:52:3
#1 0x7f55e431d9f2 in _hashmap_clear /work/build/../../src/systemd/src/basic/hashmap.c:927:33
#2 0x7f55e431d4c8 in _hashmap_free /work/build/../../src/systemd/src/basic/hashmap.c:896:17
#3 0x4de1de in ordered_hashmap_free_free_free /work/build/../../src/systemd/src/basic/hashmap.h:120:24
#4 0x4de1de in ordered_hashmap_free_free_freep /work/build/../../src/systemd/src/basic/hashmap.h:434:1
#5 0x4de1de in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-catalog.c:26:1
#6 0x4de8b8 in NaloFuzzerTestOneInput (/build/fuzz-catalog+0x4de8b8)
#7 0x4fd8c3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:611:15
#8 0x4fd0aa in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:514:3
#9 0x4fe779 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:757:19
#10 0x4ff445 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, std::__Fuzzer::allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:895:5
#11 0x4ee7af in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:912:6
#12 0x4ef078 in LLVMFuzzerRunDriver /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:925:10
#13 0x4deb35 in main (/build/fuzz-catalog+0x4deb35)
#14 0x7f55e3a32082 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24082) (BuildId: 1878e6b475720c7c51969e69ab2d276fae6d1dee)
#15 0x41f7cd in _start (/build/fuzz-catalog+0x41f7cd)
DEDUP_TOKEN: __interceptor_free--_hashmap_clear--_hashmap_free
0x611000039fc0 is located 0 bytes inside of 224-byte region [0x611000039fc0,0x61100003a0a0)
freed by thread T0 here:
#0 0x4a0962 in __interceptor_free /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:52:3
#1 0x7f55e451493d in freep /work/build/../../src/systemd/src/basic/alloc-util.h:107:22
#2 0x7f55e451493d in finish_item /work/build/../../src/systemd/src/libsystemd/sd-journal/catalog.c:187:1
#3 0x7f55e4513e56 in catalog_import_file /work/build/../../src/systemd/src/libsystemd/sd-journal/catalog.c:313:45
#4 0x4de1be in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-catalog.c:23:16
#5 0x4de8b8 in NaloFuzzerTestOneInput (/build/fuzz-catalog+0x4de8b8)
#6 0x4fd8c3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:611:15
#7 0x4fd0aa in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:514:3
#8 0x4fe779 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:757:19
#9 0x4ff445 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, std::__Fuzzer::allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:895:5
#10 0x4ee7af in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:912:6
#11 0x4ef078 in LLVMFuzzerRunDriver /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:925:10
#12 0x4deb35 in main (/build/fuzz-catalog+0x4deb35)
#13 0x7f55e3a32082 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24082) (BuildId: 1878e6b475720c7c51969e69ab2d276fae6d1dee)
DEDUP_TOKEN: __interceptor_free--freep--finish_item
previously allocated by thread T0 here:
#0 0x4a0c06 in __interceptor_malloc /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:69:3
#1 0x4de539 in malloc (/build/fuzz-catalog+0x4de539)
#2 0x7f55e42bf96b in memdup /work/build/../../src/systemd/src/basic/alloc-util.c:16:15
#3 0x7f55e451475d in finish_item /work/build/../../src/systemd/src/libsystemd/sd-journal/catalog.c:176:28
#4 0x7f55e4513e56 in catalog_import_file /work/build/../../src/systemd/src/libsystemd/sd-journal/catalog.c:313:45
#5 0x4de1be in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/fuzz/fuzz-catalog.c:23:16
#6 0x4de8b8 in NaloFuzzerTestOneInput (/build/fuzz-catalog+0x4de8b8)
#7 0x4fd8c3 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:611:15
#8 0x4fd0aa in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:514:3
#9 0x4fe779 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:757:19
#10 0x4ff445 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, std::__Fuzzer::allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:895:5
#11 0x4ee7af in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:912:6
#12 0x4ef078 in LLVMFuzzerRunDriver /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:925:10
#13 0x4deb35 in main (/build/fuzz-catalog+0x4deb35)
#14 0x7f55e3a32082 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24082) (BuildId: 1878e6b475720c7c51969e69ab2d276fae6d1dee)
DEDUP_TOKEN: __interceptor_malloc--malloc--memdup
SUMMARY: AddressSanitizer: double-free /src/llvm-project/compiler-rt/lib/asan/asan_malloc_linux.cpp:52:3 in __interceptor_free
Found by Nallocfuzz.
Recent gcc versions have started to trigger false positive
maybe-uninitialized warnings. Let's make sure we initialize
variables annotated with _cleanup_ to avoid these.
This reverts commit 1db6dbb1dc.
The original patch was reverted because of issue #25369. The issue was created
because it wrongly assumed that sd_journal_seek_tail() seeks to 'current' tail.
But in fact, only when a subsequent sd_journal_previous() is called that it's
pointing to the tail at that time. The concept of 'tail' in sd_journal_seek_tail()
only has a logical meaning, and a sd_journal_previous is needed. In fact, if we
look at the codes in journalctl, we can see sd_journal_seek_tail() is followed by
sd_journal_previous(). By contrary, a sd_journal_next() after a 'logical' tail does
not make much sense. So the original patch is correct, and projects that are
using 'sd_journal_next()' right after 'sd_journal_seek_tail()' should do fixes
as in https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/2823#note_1637715.
As it might hide a possible allocation error since it uses
the returns_nonnull attribute:
AddressSanitizer:DEADLYSIGNAL
=================================================================
==8==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000004 (pc 0x7f317897db8d bp 0x7ffd436fe9a0 sp 0x7ffd436fe970 T0)
==8==The signal is caused by a WRITE memory access.
==8==Hint: address points to the zero page.
SCARINESS: 10 (null-deref)
#0 0x7f317897db8d in source_new /work/build/../../src/systemd/src/libsystemd/sd-event/sd-event.c:1214:18
#1 0x7f317897e68c in sd_event_add_time /work/build/../../src/systemd/src/libsystemd/sd-event/sd-event.c:1417:13
#2 0x7f317897a0f6 in event_reset_time /work/build/../../src/systemd/src/libsystemd/sd-event/event-util.c:68:21
#3 0x4e2c8e in client_initialize_time_events /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp-client.c:1366:13
#4 0x4eb0fd in client_initialize_events /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp-client.c:1380:9
#5 0x4eb0fd in client_start_delayed /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp-client.c:1410:16
#6 0x4e30aa in client_start /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp-client.c:1415:16
#7 0x4e30aa in sd_dhcp_client_start /work/build/../../src/systemd/src/libsystemd-network/sd-dhcp-client.c:2045:13
#8 0x4e700e in LLVMFuzzerTestOneInput /work/build/../../src/systemd/src/libsystemd-network/fuzz-dhcp-client.c:73:15
#9 0x5062f8 in NaloFuzzerTestOneInput (/build/fuzz-dhcp-client+0x5062f8)
#10 0x525283 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:611:15
#11 0x524a6a in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:514:3
#12 0x526139 in fuzzer::Fuzzer::MutateAndTestOne() /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:757:19
#13 0x526e05 in fuzzer::Fuzzer::Loop(std::__Fuzzer::vector<fuzzer::SizedFile, std::__Fuzzer::allocator<fuzzer::SizedFile> >&) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerLoop.cpp:895:5
#14 0x51616f in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:912:6
#15 0x516a38 in LLVMFuzzerRunDriver /src/llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:925:10
#16 0x506555 in main (/build/fuzz-dhcp-client+0x506555)
#17 0x7f3177ce3082 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24082) (BuildId: 1878e6b475720c7c51969e69ab2d276fae6d1dee)
#18 0x420c4d in _start (/build/fuzz-dhcp-client+0x420c4d)
Found by Nallocfuzz.
This in unnecessarilly unpleasant: the code might report about a bus
connection, e.g. in an error message or assert. Let's let it query
the name of the object.
This partially reverts f4b2933ee7.
The code has an explicit fallback using runtime_scope_to_string(), which
is also documented in the man page. So -ENXIO should only be returned when
the fallback doesn't work, i.e. bus->runtime_scope == -EINVAL.
Fixup for f4b2933ee7.
This should fix the following errors during boot:
May 18 16:05:37 fedora systemd-update-utmp[263]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:38 fedora systemctl[360]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:38 fedora systemctl[363]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:38 fedora systemd-update-utmp[372]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:38 fedora @ystemctl[387]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:40 fedora systemd-update-utmp[477]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:41 fedora systemd-homed[509]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:41 fedora systemd-logind[510]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:41 fedora systemd-update-utmp[529]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:42 fedora systemd-user-runtime-dir[531]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:42 fedora systemctl[542]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
May 18 16:05:42 fedora systemd-hostnamed[556]: Assertion 'bus->description' failed at src/libsystemd/sd-bus/sd-bus.c:4201, function sd_bus_get_description(). Ignoring.
Now that clients might convey comm/description strings via the sockaddr,
let's actually use them on the other side, read the data via
getpeername() parse it, and include it in the "owner" creds (which is
how we call the peer's creds).
Let's pass some additional meta information along bus connections
without actually altering the communication protocol.
Pass the client comm and client description string of the bus via
including it in the abstract namespace client socket address we connect
to. This is purely informational (and entirely user controlled), but has
the benefit that servers can make use of the information if they want,
but really don't have to. It works entirely transparently.
This takes inspiration from how we convey similar information via
credential socket connections.
GCC document [1] says:
The pure attribute prohibits a function from modifying the state
of the program that is observable by means other than inspecting
the function’s return value.
And there is an example:
`int hash (char *) __attribute__ ((pure));`
... Even though hash takes a non-const pointer argument it must
not modify the array it points to, ...
But we are modifying the object pointed to by the pointer u, which is
clearly a violation of the semantic of pure.
With -ftrivial-auto-var-init (enabled by -Dmode=release), on some
targets (GCC 12.2 on AArch64 and GCC 13.1 on x86_64) performs an
optimization: as the variable "u" in bus_match_parse has been
zero-initialized (by the -ftrivial-auto-var-init option) and never
modified (because a "pure" bus_message_type_from_string is not allowed
to modify it), "u" will be always 0.
Then 0 is used to initialize .value_u8 field of struct
bus_match_component. This then causes a infinite event loop, so
"systemctl restart" never stops, and pam_systemd timeouts communicating
with logind, etc.
So we should remove the "pure" attribute here.
Fixes#26395.
[1]:https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute
Lennart Poettering
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Daan De Meyer
Frantisek Sumsal
David Tardon
Chen Qi
Xi Ruoyao