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kmod/core: fix relocation writes across page boundaries 

The integration test suite was intermittently giving the following
error:

  [192685.907072] kpatch: write to 0xffffffffa082bffe failed for symbol call_netdevice_notifiers_info

The error was caused by a write across a page boundary without first
making the second page read/write.
This commit is contained in:
Josh Poimboeuf 2014-06-26 16:36:26 -05:00
parent 132aa1bbc6
commit c36e90e188
1 changed files with 5 additions and 3 deletions
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8
kmod/core/core.c
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@ -509,7 +509,7 @@ static unsigned long kpatch_find_module_symbol(struct module *mod,
static int kpatch_write_relocations(struct kpatch_module *kpmod,
struct kpatch_object *object)
{
int ret, size, readonly = 0;
int ret, size, readonly = 0, numpages;
struct kpatch_dynrela *dynrela;
u64 loc, val;
unsigned long core = (unsigned long)kpmod->mod->module_core;
@ -577,13 +577,15 @@ static int kpatch_write_relocations(struct kpatch_module *kpmod,
return -EINVAL;
}
numpages = (PAGE_SIZE - (loc & ~PAGE_MASK) >= size) ? 1 : 2;
if (readonly)
set_memory_rw(loc & PAGE_MASK, 1);
set_memory_rw(loc & PAGE_MASK, numpages);
ret = probe_kernel_write((void *)loc, &val, size);
if (readonly)
set_memory_ro(loc & PAGE_MASK, 1);
set_memory_ro(loc & PAGE_MASK, numpages);
if (ret) {
pr_err("write to 0x%llx failed for symbol %s\n",