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bpf: fix unlocking of jited image when module ronx not set

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Eric and Willem reported that they recently saw random crashes when
JIT was in use and bisected this to 74451e66d5 ("bpf: make jited
programs visible in traces"). Issue was that the consolidation part
added bpf_jit_binary_unlock_ro() that would unlock previously made
read-only memory back to read-write. However, DEBUG_SET_MODULE_RONX
cannot be used for this to test for presence of set_memory_*()
functions. We need to use ARCH_HAS_SET_MEMORY instead to fix this;
also add the corresponding bpf_jit_binary_lock_ro() to filter.h.

Fixes: 74451e66d5 ("bpf: make jited programs visible in traces")
Reported-by: Eric Dumazet <edumazet@google.com>
Reported-by: Willem de Bruijn <willemb@google.com>
Bisected-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann 2017-02-21 16:09:34 +01:00 committed by David S. Miller
parent d2852a2240
commit 9d876e79df
4 changed files with 14 additions and 5 deletions
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2
arch/arm64/net/bpf_jit_comp.c
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@ -898,7 +898,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
bpf_flush_icache(header, ctx.image + ctx.idx);
set_memory_ro((unsigned long)header, header->pages);
bpf_jit_binary_lock_ro(header);
prog->bpf_func = (void *)ctx.image;
prog->jited = 1;

2
arch/s390/net/bpf_jit_comp.c
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@ -1327,7 +1327,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *fp)
print_fn_code(jit.prg_buf, jit.size_prg);
}
if (jit.prg_buf) {
set_memory_ro((unsigned long)header, header->pages);
bpf_jit_binary_lock_ro(header);
fp->bpf_func = (void *) jit.prg_buf;
fp->jited = 1;
}

2
arch/x86/net/bpf_jit_comp.c
View File

@ -1165,7 +1165,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
if (image) {
bpf_flush_icache(header, image + proglen);
set_memory_ro((unsigned long)header, header->pages);
bpf_jit_binary_lock_ro(header);
prog->bpf_func = (void *)image;
prog->jited = 1;
} else {

13
include/linux/filter.h
View File

@ -551,7 +551,7 @@ static inline bool bpf_prog_was_classic(const struct bpf_prog *prog)
#define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
#ifdef CONFIG_DEBUG_SET_MODULE_RONX
#ifdef CONFIG_ARCH_HAS_SET_MEMORY
static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
{
set_memory_ro((unsigned long)fp, fp->pages);
@ -562,6 +562,11 @@ static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
set_memory_rw((unsigned long)fp, fp->pages);
}
static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
{
set_memory_ro((unsigned long)hdr, hdr->pages);
}
static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
{
set_memory_rw((unsigned long)hdr, hdr->pages);
@ -575,10 +580,14 @@ static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
{
}
static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
{
}
static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
{
}
#endif /* CONFIG_DEBUG_SET_MODULE_RONX */
#endif /* CONFIG_ARCH_HAS_SET_MEMORY */
static inline struct bpf_binary_header *
bpf_jit_binary_hdr(const struct bpf_prog *fp)