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| author | Kees Cook <keescook@chromium.org> | 2024-02-01 18:32:58 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-07 10:05:45 +0200 |
| commit | 756992b8d50638a7a071d4bb9841ca444cb7d4c6 (patch) | |
| tree | 806c87a7ac89a0f663fd0a5e4f118ceb9a12b7d0 | |
| parent | 0ef6e49881b6b50ac454cb9d6501d009fdceb6fc (diff) | |
| download | linux-756992b8d50638a7a071d4bb9841ca444cb7d4c6.tar.gz linux-756992b8d50638a7a071d4bb9841ca444cb7d4c6.tar.bz2 linux-756992b8d50638a7a071d4bb9841ca444cb7d4c6.zip | |
ARM: 9350/1: fault: Implement copy_from_kernel_nofault_allowed()
commit 169f9102f9198b04afffa6164372a4ba4070f412 upstream.
Under PAN emulation when dumping backtraces from things like the
LKDTM EXEC_USERSPACE test[1], a double fault (which would hang a CPU)
would happen because of dump_instr() attempting to read a userspace
address. Make sure copy_from_kernel_nofault() does not attempt this
any more.
Closes: https://lava.sirena.org.uk/scheduler/job/497571
Link: https://lore.kernel.org/all/202401181125.D48DCB4C@keescook/ [1]
Reported-by: Mark Brown <broonie@kernel.org>
Suggested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Cc: Wang Kefeng <wangkefeng.wang@huawei.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm/mm/fault.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index b0db85310331..09230ff12188 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -25,6 +25,13 @@ #include "fault.h" +bool copy_from_kernel_nofault_allowed(const void *unsafe_src, size_t size) +{ + unsigned long addr = (unsigned long)unsafe_src; + + return addr >= TASK_SIZE && ULONG_MAX - addr >= size; +} + #ifdef CONFIG_MMU /* |