From 44283b4f2ff4dd8976209b6438e4279a0f3f07d5 Mon Sep 17 00:00:00 2001 From: Szabolcs Nagy Date: Fri, 21 Oct 2022 12:35:33 +0100 Subject: cheri: malloc: Ensure the mappings have RW permission The arena allocator incrementally applies RW mprotect to a PROT_NONE mapping. Use PROT_MAX to ensure the pointers derived from the original mapping have RW capability permission. --- malloc/malloc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/malloc/malloc.c b/malloc/malloc.c index cc222eaba2..392116a5ac 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -1284,8 +1284,16 @@ static mchunkptr mremap_chunk(mchunkptr p, size_t new_size); # define MAP_NORESERVE 0 #endif +/* Allow RW mprotect later, on CHERI this means RW capability permission. */ +#ifdef PROT_MAX +# define PROT_MAX_RW PROT_MAX (PROT_READ | PROT_WRITE) +#else +# define PROT_MAX_RW 0 +#endif + #define MMAP(addr, size, prot, flags) \ - __mmap((addr), (size), (prot), (flags)|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0) + __mmap((addr), (size), (prot)|PROT_MAX_RW, \ + (flags)|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0) /* -- cgit 1.4.1