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Alexander Lobakin 0aeaadc52b MIPS: fix fortify panic when copying asm exception handlers
[ Upstream commit d17b66417308996e7e64b270a3c7f3c1fbd4cfc8 ]

With KCFLAGS="-O3", I was able to trigger a fortify-source
memcpy() overflow panic on set_vi_srs_handler().
Although O3 level is not supported in the mainline, under some
conditions that may've happened with any optimization settings,
it's just a matter of inlining luck. The panic itself is correct,
more precisely, 50/50 false-positive and not at the same time.
From the one side, no real overflow happens. Exception handler
defined in asm just gets copied to some reserved places in the
memory.
But the reason behind is that C code refers to that exception
handler declares it as `char`, i.e. something of 1 byte length.
It's obvious that the asm function itself is way more than 1 byte,
so fortify logics thought we are going to past the symbol declared.
The standard way to refer to asm symbols from C code which is not
supposed to be called from C is to declare them as
`extern const u8[]`. This is fully correct from any point of view,
as any code itself is just a bunch of bytes (including 0 as it is
for syms like _stext/_etext/etc.), and the exact size is not known
at the moment of compilation.
Adjust the type of the except_vec_vi_*() and related variables.
Make set_handler() take `const` as a second argument to avoid
cast-away warnings and give a little more room for optimization.

Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-04-15 14:18:34 +02:00
arch MIPS: fix fortify panic when copying asm exception handlers 2022-04-15 14:18:34 +02:00
block Revert "Revert "block, bfq: honor already-setup queue merges"" 2022-04-15 14:18:23 +02:00
certs
crypto crypto: authenc - Fix sleep in atomic context in decrypt_tail 2022-04-15 14:18:04 +02:00
Documentation dt-bindings: spi: mxic: The interrupt property is not mandatory 2022-04-15 14:18:30 +02:00
drivers bnxt_en: Eliminate unintended link toggle during FW reset 2022-04-15 14:18:34 +02:00
fs ubifs: Rectify space amount budget for mkdir/tmpfile operations 2022-04-15 14:18:31 +02:00
include ipv4: Invalidate neighbour for broadcast address upon address addition 2022-04-15 14:18:33 +02:00
init bpf: Add kconfig knob for disabling unpriv bpf by default 2022-02-16 12:52:49 +01:00
ipc shm: extend forced shm destroy to support objects from several IPC nses 2021-12-01 09:23:35 +01:00
kernel dma-debug: fix return value of __setup handlers 2022-04-15 14:18:18 +02:00
lib XArray: Update the LRU list in xas_split() 2022-04-15 14:18:28 +02:00
LICENSES
mm mm/usercopy: return 1 from hardened_usercopy __setup() handler 2022-04-15 14:18:30 +02:00
net net/smc: correct settings of RMB window update limit 2022-04-15 14:18:34 +02:00
samples samples/kretprobes: Fix return value if register_kretprobe() failed 2021-11-17 09:48:39 +01:00
scripts gcc-plugins/stackleak: Exactly match strings instead of prefixes 2022-04-15 14:18:22 +02:00
security Fix incorrect type in assignment of ipv6 port for audit 2022-04-15 14:18:22 +02:00
sound ASoC: topology: Allow TLV control to be either read or write 2022-04-15 14:18:30 +02:00
tools bpf: Fix comment for helper bpf_current_task_under_cgroup() 2022-04-15 14:18:30 +02:00
usr
virt KVM: Prevent module exit until all VMs are freed 2022-04-15 14:18:27 +02:00
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Makefile Linux 5.4.188 2022-03-28 08:46:49 +02:00
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