[PATCH -fixes] riscv: Fix wrong usage of lm_alias() when splitting a huge linear mapping

Alexandre Ghiti
2023-12-11T14:20:27Z

lm_alias() can only be used on kernel mappings since it explicitly uses
__pa_symbol(), so simply fix this by checking where the address belongs
to before.

Fixes: 311cd2f6e253 ("riscv: Fix set_memory_XX() and set_direct_map_XX() by splitting huge linear mappings")
Reported-by: syzbot+afb726d49f84c8d95ee1@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-riscv/000000000000620dd0060c02c5e1@google.com/
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
arch/riscv/mm/pageattr.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index fc5fc4f785c4..f5f8aa1d38d6 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -304,9 +304,16 @@ static int __set_memory(unsigned long addr, int numpages, pgprot_t set_mask,
if (ret)
goto unlock;
}
- } else if (is_kernel_mapping(start) || is_linear_mapping(start)) {
- lm_start = (unsigned long)lm_alias(start);
- lm_end = (unsigned long)lm_alias(end);
+ } else {
+ if (is_kernel_mapping(start)) {
+ lm_start = (unsigned long)lm_alias(start);
+ lm_end = (unsigned long)lm_alias(end);
+ } else if (is_linear_mapping(start)) {
+ lm_start = start;
+ lm_end = end;
+ } else {
+ goto unlock;
+ }

ret = split_linear_mapping(lm_start, lm_end);
if (ret)
--
2.39.2