netlink: Re-derive the base capability of the snl msg_buffer in realloc #2281
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If the new base pointer obtained in snl_realloc_msg_buffer does not have the same bounds as the original base pointer, we need to re-derive all the capabilities that are relative to the base.
bsdjhb
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Dec 30, 2024
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+1102
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+1104
| int hdr_off = (char *)(nw->hdr) - nw->base; | ||
| nw->hdr = (struct nlmsghdr *) | ||
| (void *)((char *)nw->base + hdr_off); |
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Suggested change
| int hdr_off = (char *)(nw->hdr) - nw->base; | |
| nw->hdr = (struct nlmsghdr *) | |
| (void *)((char *)nw->base + hdr_off); | |
| int hdr_off = (char *)(nw->hdr) - nw->base; | |
| nw->hdr = (struct nlmsghdr *) | |
| (void *)((char *)nw->base + hdr_off); |
to match existing formatting
| @@ -1095,6 +1095,16 @@ snl_realloc_msg_buffer(struct snl_writer *nw, size_t sz) | |||
| } | |||
| nw->base = (char *)new_base; | |||
| } | |||
| #ifdef __CHERI_PURE_CAPABILITY__ | |||
| if (cheri_getlen(new_base) != cheri_getlen(nw->base)) { | |||
| nw->base = (char *)cheri_setboundsexact(new_base, nw->size); | |||
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Doesn't snl_allocz already do this?
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If the new base pointer obtained in snl_realloc_msg_buffer does not have the same bounds as the original base pointer, we need to re-derive all the capabilities that are relative to the base. This was found while fuzzing.
Tagging @YiChenChai.