commit c0b067588a4836b762cfc6a4c83f122ca1dbb93a upstream. This reverts commit 46d21ec067490ab9cdcc89b9de5aae28786a8b8e. The tests were made with a specific workload, further tests on a recently updated fedora 38 system with a system wide perf.data file shows 'perf report' taking excessive time resolving inlines in vmlinux, so lets revert this until a full investigation and improvement on the addr2line support code is made. Reported-by: Jesper Dangaard Brouer <hawk@kernel.org> Acked-by: Artem Savkov <asavkov@redhat.com> Tested-by: Jesper Dangaard Brouer <hawk@kernel.org> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Milian Wolff <milian.wolff@kdab.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/ZMl8VyhdwhClTM5g@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 855067defa36b1f9effad8c219d9a85b655cf500 ]
This test verifies whether the encapsulated packets have the correct
configured TTL. It does so by sending ICMP packets through the test
topology and mirroring them to a gretap netdevice. On a busy host
however, more than just the test ICMP packets may end up flowing
through the topology, get mirrored, and counted. This leads to
potential spurious failures as the test observes much more mirrored
packets than the sent test packets, and assumes a bug.
Fix this by tightening up the mirror action match. Change it from
matchall to a flower classifier matching on ICMP packets specifically.
Fixes: 45315673e0c5 ("selftests: forwarding: Test changes in mirror-to-gretap")
Signed-off-by: Petr Machata <petrm@nvidia.com>
Tested-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 833fd800bf56b74d39d71d3f5936dffb3e0409c6 upstream.
The kprobes optimization check can_optimize() calls
insn_is_indirect_jump() to detect indirect jump instructions in
a target function. If any is found, creating an optprobe is disallowed
in the function because the jump could be from a jump table and could
potentially land in the middle of the target optprobe.
With retpolines, insn_is_indirect_jump() additionally looks for calls to
indirect thunks which the compiler potentially used to replace original
jumps. This extra check is however unnecessary because jump tables are
disabled when the kernel is built with retpolines. The same is currently
the case with IBT.
Based on this observation, remove the logic to look for calls to
indirect thunks and skip the check for indirect jumps altogether if the
kernel is built with retpolines or IBT. Remove subsequently the symbols
__indirect_thunk_start and __indirect_thunk_end which are no longer
needed.
Dropping this logic indirectly fixes a problem where the range
[__indirect_thunk_start, __indirect_thunk_end] wrongly included also the
return thunk. It caused that machines which used the return thunk as
a mitigation and didn't have it patched by any alternative ended up not
being able to use optprobes in any regular function.
Fixes: 0b53c374b9ef ("x86/retpoline: Use -mfunction-return")
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20230711091952.27944-3-petr.pavlu@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 79cd2a11224eab86d6673fe8a11d2046ae9d2757 upstream.
The linker script arch/x86/kernel/vmlinux.lds.S matches the thunk
sections ".text.__x86.*" from arch/x86/lib/retpoline.S as follows:
.text {
[...]
TEXT_TEXT
[...]
__indirect_thunk_start = .;
*(.text.__x86.*)
__indirect_thunk_end = .;
[...]
}
Macro TEXT_TEXT references TEXT_MAIN which normally expands to only
".text". However, with CONFIG_LTO_CLANG, TEXT_MAIN becomes
".text .text.[0-9a-zA-Z_]*" which wrongly matches also the thunk
sections. The output layout is then different than expected. For
instance, the currently defined range [__indirect_thunk_start,
__indirect_thunk_end] becomes empty.
Prevent the problem by using ".." as the first separator, for example,
".text..__x86.indirect_thunk". This pattern is utilized by other
explicit section names which start with one of the standard prefixes,
such as ".text" or ".data", and that need to be individually selected in
the linker script.
[ nathan: Fix conflicts with SRSO and fold in fix issue brought up by
Andrew Cooper in post-review:
https://lore.kernel.org/20230803230323.1478869-1-andrew.cooper3@citrix.com ]
Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO")
Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230711091952.27944-2-petr.pavlu@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit dbf46008775516f7f25c95b7760041c286299783 upstream.
For stack-validation of a frame-pointer build, objtool validates that
every CALL instruction is preceded by a frame-setup. The new SRSO
return thunks violate this with their RSB stuffing trickery.
Extend the __fentry__ exception to also cover the embedded_insn case
used for this. This cures:
vmlinux.o: warning: objtool: srso_untrain_ret+0xd: call without frame pointer save/setup
Fixes: 4ae68b26c3ab ("objtool/x86: Fix SRSO mess")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20230816115921.GH980931@hirez.programming.kicks-ass.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d025b7bac07a6e90b6b98b487f88854ad9247c39 upstream. Rename the original retbleed return thunk and untrain_ret to retbleed_return_thunk() and retbleed_untrain_ret(). No functional changes. Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Link: https://lore.kernel.org/r/20230814121148.909378169@infradead.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit d43490d0ab824023e11d0b57d0aeec17a6e0ca13 upstream.
Use the existing configurable return thunk. There is absolute no
justification for having created this __x86_return_thunk alternative.
To clarify, the whole thing looks like:
Zen3/4 does:
srso_alias_untrain_ret:
nop2
lfence
jmp srso_alias_return_thunk
int3
srso_alias_safe_ret: // aliasses srso_alias_untrain_ret just so
add $8, %rsp
ret
int3
srso_alias_return_thunk:
call srso_alias_safe_ret
ud2
While Zen1/2 does:
srso_untrain_ret:
movabs $foo, %rax
lfence
call srso_safe_ret (jmp srso_return_thunk ?)
int3
srso_safe_ret: // embedded in movabs instruction
add $8,%rsp
ret
int3
srso_return_thunk:
call srso_safe_ret
ud2
While retbleed does:
zen_untrain_ret:
test $0xcc, %bl
lfence
jmp zen_return_thunk
int3
zen_return_thunk: // embedded in the test instruction
ret
int3
Where Zen1/2 flush the BTB entry using the instruction decoder trick
(test,movabs) Zen3/4 use BTB aliasing. SRSO adds a return sequence
(srso_safe_ret()) which forces the function return instruction to
speculate into a trap (UD2). This RET will then mispredict and
execution will continue at the return site read from the top of the
stack.
Pick one of three options at boot (evey function can only ever return
once).
[ bp: Fixup commit message uarch details and add them in a comment in
the code too. Add a comment about the srso_select_mitigation()
dependency on retbleed_select_mitigation(). Add moar ifdeffery for
32-bit builds. Add a dummy srso_untrain_ret_alias() definition for
32-bit alternatives needing the symbol. ]
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.842775684@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4ae68b26c3ab5a82aa271e6e9fc9b1a06e1d6b40 upstream.
Objtool --rethunk does two things:
- it collects all (tail) call's of __x86_return_thunk and places them
into .return_sites. These are typically compiler generated, but
RET also emits this same.
- it fudges the validation of the __x86_return_thunk symbol; because
this symbol is inside another instruction, it can't actually find
the instruction pointed to by the symbol offset and gets upset.
Because these two things pertained to the same symbol, there was no
pressing need to separate these two separate things.
However, alas, along comes SRSO and more crazy things to deal with
appeared.
The SRSO patch itself added the following symbol names to identify as
rethunk:
'srso_untrain_ret', 'srso_safe_ret' and '__ret'
Where '__ret' is the old retbleed return thunk, 'srso_safe_ret' is a
new similarly embedded return thunk, and 'srso_untrain_ret' is
completely unrelated to anything the above does (and was only included
because of that INT3 vs UD2 issue fixed previous).
Clear things up by adding a second category for the embedded instruction
thing.
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.704502245@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 8743aeff5bc4dcb5b87b43765f48d5ac3ad7dd9f upstream.
A netlink dump callback can return a positive number to signal that more
information needs to be dumped or zero to signal that the dump is
complete. In the second case, the core netlink code will append the
NLMSG_DONE message to the skb in order to indicate to user space that
the dump is complete.
The nexthop bucket dump callback always returns a positive number if
nexthop buckets were filled in the provided skb, even if the dump is
complete. This means that a dump will span at least two recvmsg() calls
as long as nexthop buckets are present. In the last recvmsg() call the
dump callback will not fill in any nexthop buckets because the previous
call indicated that the dump should restart from the last dumped nexthop
ID plus one.
# ip link add name dummy1 up type dummy
# ip nexthop add id 1 dev dummy1
# ip nexthop add id 10 group 1 type resilient buckets 2
# strace -e sendto,recvmsg -s 5 ip nexthop bucket
sendto(3, [[{nlmsg_len=24, nlmsg_type=RTM_GETNEXTHOPBUCKET, nlmsg_flags=NLM_F_REQUEST|NLM_F_DUMP, nlmsg_seq=1691396980, nlmsg_pid=0}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], {nlmsg_len=0, nlmsg_type=0 /* NLMSG_??? */, nlmsg_flags=0, nlmsg_seq=0, nlmsg_pid=0}], 152, 0, NULL, 0) = 152
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 128
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[[{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396980, nlmsg_pid=347}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], [{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396980, nlmsg_pid=347}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}]], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 128
id 10 index 0 idle_time 6.66 nhid 1
id 10 index 1 idle_time 6.66 nhid 1
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 20
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{nlmsg_len=20, nlmsg_type=NLMSG_DONE, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396980, nlmsg_pid=347}, 0], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20
+++ exited with 0 +++
This behavior is both inefficient and buggy. If the last nexthop to be
dumped had the maximum ID of 0xffffffff, then the dump will restart from
0 (0xffffffff + 1) and never end:
# ip link add name dummy1 up type dummy
# ip nexthop add id 1 dev dummy1
# ip nexthop add id $((2**32-1)) group 1 type resilient buckets 2
# ip nexthop bucket
id 4294967295 index 0 idle_time 5.55 nhid 1
id 4294967295 index 1 idle_time 5.55 nhid 1
id 4294967295 index 0 idle_time 5.55 nhid 1
id 4294967295 index 1 idle_time 5.55 nhid 1
[...]
Fix by adjusting the dump callback to return zero when the dump is
complete. After the fix only one recvmsg() call is made and the
NLMSG_DONE message is appended to the RTM_NEWNEXTHOPBUCKET responses:
# ip link add name dummy1 up type dummy
# ip nexthop add id 1 dev dummy1
# ip nexthop add id $((2**32-1)) group 1 type resilient buckets 2
# strace -e sendto,recvmsg -s 5 ip nexthop bucket
sendto(3, [[{nlmsg_len=24, nlmsg_type=RTM_GETNEXTHOPBUCKET, nlmsg_flags=NLM_F_REQUEST|NLM_F_DUMP, nlmsg_seq=1691396737, nlmsg_pid=0}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], {nlmsg_len=0, nlmsg_type=0 /* NLMSG_??? */, nlmsg_flags=0, nlmsg_seq=0, nlmsg_pid=0}], 152, 0, NULL, 0) = 152
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 148
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[[{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396737, nlmsg_pid=350}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], [{nlmsg_len=64, nlmsg_type=RTM_NEWNEXTHOPBUCKET, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396737, nlmsg_pid=350}, {family=AF_UNSPEC, data="\x00\x00\x00\x00\x00"...}], [{nlmsg_len=20, nlmsg_type=NLMSG_DONE, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691396737, nlmsg_pid=350}, 0]], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 148
id 4294967295 index 0 idle_time 6.61 nhid 1
id 4294967295 index 1 idle_time 6.61 nhid 1
+++ exited with 0 +++
Note that if the NLMSG_DONE message cannot be appended because of size
limitations, then another recvmsg() will be needed, but the core netlink
code will not invoke the dump callback and simply reply with a
NLMSG_DONE message since it knows that the callback previously returned
zero.
Add a test that fails before the fix:
# ./fib_nexthops.sh -t basic_res
[...]
TEST: Maximum nexthop ID dump [FAIL]
[...]
And passes after it:
# ./fib_nexthops.sh -t basic_res
[...]
TEST: Maximum nexthop ID dump [ OK ]
[...]
Fixes: 8a1bbabb034d ("nexthop: Add netlink handlers for bucket dump")
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230808075233.3337922-4-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 913f60cacda73ccac8eead94983e5884c03e04cd upstream.
A netlink dump callback can return a positive number to signal that more
information needs to be dumped or zero to signal that the dump is
complete. In the second case, the core netlink code will append the
NLMSG_DONE message to the skb in order to indicate to user space that
the dump is complete.
The nexthop dump callback always returns a positive number if nexthops
were filled in the provided skb, even if the dump is complete. This
means that a dump will span at least two recvmsg() calls as long as
nexthops are present. In the last recvmsg() call the dump callback will
not fill in any nexthops because the previous call indicated that the
dump should restart from the last dumped nexthop ID plus one.
# ip nexthop add id 1 blackhole
# strace -e sendto,recvmsg -s 5 ip nexthop
sendto(3, [[{nlmsg_len=24, nlmsg_type=RTM_GETNEXTHOP, nlmsg_flags=NLM_F_REQUEST|NLM_F_DUMP, nlmsg_seq=1691394315, nlmsg_pid=0}, {nh_family=AF_UNSPEC, nh_scope=RT_SCOPE_UNIVERSE, nh_protocol=RTPROT_UNSPEC, nh_flags=0}], {nlmsg_len=0, nlmsg_type=0 /* NLMSG_??? */, nlmsg_flags=0, nlmsg_seq=0, nlmsg_pid=0}], 152, 0, NULL, 0) = 152
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 36
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{nlmsg_len=36, nlmsg_type=RTM_NEWNEXTHOP, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691394315, nlmsg_pid=343}, {nh_family=AF_INET, nh_scope=RT_SCOPE_UNIVERSE, nh_protocol=RTPROT_UNSPEC, nh_flags=0}, [[{nla_len=8, nla_type=NHA_ID}, 1], {nla_len=4, nla_type=NHA_BLACKHOLE}]], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 36
id 1 blackhole
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 20
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{nlmsg_len=20, nlmsg_type=NLMSG_DONE, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691394315, nlmsg_pid=343}, 0], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20
+++ exited with 0 +++
This behavior is both inefficient and buggy. If the last nexthop to be
dumped had the maximum ID of 0xffffffff, then the dump will restart from
0 (0xffffffff + 1) and never end:
# ip nexthop add id $((2**32-1)) blackhole
# ip nexthop
id 4294967295 blackhole
id 4294967295 blackhole
[...]
Fix by adjusting the dump callback to return zero when the dump is
complete. After the fix only one recvmsg() call is made and the
NLMSG_DONE message is appended to the RTM_NEWNEXTHOP response:
# ip nexthop add id $((2**32-1)) blackhole
# strace -e sendto,recvmsg -s 5 ip nexthop
sendto(3, [[{nlmsg_len=24, nlmsg_type=RTM_GETNEXTHOP, nlmsg_flags=NLM_F_REQUEST|NLM_F_DUMP, nlmsg_seq=1691394080, nlmsg_pid=0}, {nh_family=AF_UNSPEC, nh_scope=RT_SCOPE_UNIVERSE, nh_protocol=RTPROT_UNSPEC, nh_flags=0}], {nlmsg_len=0, nlmsg_type=0 /* NLMSG_??? */, nlmsg_flags=0, nlmsg_seq=0, nlmsg_pid=0}], 152, 0, NULL, 0) = 152
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=NULL, iov_len=0}], msg_iovlen=1, msg_controllen=0, msg_flags=MSG_TRUNC}, MSG_PEEK|MSG_TRUNC) = 56
recvmsg(3, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[[{nlmsg_len=36, nlmsg_type=RTM_NEWNEXTHOP, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691394080, nlmsg_pid=342}, {nh_family=AF_INET, nh_scope=RT_SCOPE_UNIVERSE, nh_protocol=RTPROT_UNSPEC, nh_flags=0}, [[{nla_len=8, nla_type=NHA_ID}, 4294967295], {nla_len=4, nla_type=NHA_BLACKHOLE}]], [{nlmsg_len=20, nlmsg_type=NLMSG_DONE, nlmsg_flags=NLM_F_MULTI, nlmsg_seq=1691394080, nlmsg_pid=342}, 0]], iov_len=32768}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 56
id 4294967295 blackhole
+++ exited with 0 +++
Note that if the NLMSG_DONE message cannot be appended because of size
limitations, then another recvmsg() will be needed, but the core netlink
code will not invoke the dump callback and simply reply with a
NLMSG_DONE message since it knows that the callback previously returned
zero.
Add a test that fails before the fix:
# ./fib_nexthops.sh -t basic
[...]
TEST: Maximum nexthop ID dump [FAIL]
[...]
And passes after it:
# ./fib_nexthops.sh -t basic
[...]
TEST: Maximum nexthop ID dump [ OK ]
[...]
Fixes: ab84be7e54fc ("net: Initial nexthop code")
Reported-by: Petr Machata <petrm@nvidia.com>
Closes: https://lore.kernel.org/netdev/87sf91enuf.fsf@nvidia.com/
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20230808075233.3337922-2-idosch@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>