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author | Russell King <rmk+kernel@armlinux.org.uk> | 2021-01-29 10:19:07 +0000 |
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committer | Russell King <rmk+kernel@armlinux.org.uk> | 2021-02-05 10:23:00 +0000 |
commit | 9c698bff66ab4914bb3d71da7dc6112519bde23e (patch) | |
tree | ffbe22801c9afde748a568d3db0f5f7e072ba119 /arch/arm | |
parent | 538eea5362a1179dfa7770dd2b6607dc30cc50c6 (diff) | |
download | linux-9c698bff66ab4914bb3d71da7dc6112519bde23e.tar.bz2 |
ARM: ensure the signal page contains defined contents
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>
Diffstat (limited to 'arch/arm')
-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 9d2e916121be..a3a38d0a4c85 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -693,18 +693,20 @@ 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; } |