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| author | Russell King <rmk+kernel@armlinux.org.uk> | 2021-01-29 13:19:07 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-02-23 17:00:57 +0300 |
| commit | 80ef523d2cb719c3de66787e922a96b5099d2fbb (patch) | |
| tree | 32123d0e78fbfcaa0b031c3367d1808569ba1907 | |
| parent | 3502f652931cb728d0eeaf9aa919ab7d2cb24d1d (diff) | |
| download | linux-80ef523d2cb719c3de66787e922a96b5099d2fbb.tar.xz | |
ARM: ensure the signal page contains defined contents
[ Upstream commit 9c698bff66ab4914bb3d71da7dc6112519bde23e ]
Ensure that the signal page contains our poison instruction to increase
the protection against ROP attacks and also contains well defined
contents.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/arm/kernel/signal.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index b908382b69ff..1c01358b9b6d 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -697,18 +697,20 @@ struct page *get_signal_page(void) addr = page_address(page); + /* Poison the entire page */ + memset32(addr, __opcode_to_mem_arm(0xe7fddef1), + PAGE_SIZE / sizeof(u32)); + /* Give the signal return code some randomness */ offset = 0x200 + (get_random_int() & 0x7fc); signal_return_offset = offset; - /* - * Copy signal return handlers into the vector page, and - * set sigreturn to be a pointer to these. - */ + /* Copy signal return handlers into the page */ memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); - ptr = (unsigned long)addr + offset; - flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); + /* Flush out all instructions in this page */ + ptr = (unsigned long)addr; + flush_icache_range(ptr, ptr + PAGE_SIZE); return page; } |