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-rw-r--r--fs/coredump.c45
1 files changed, 42 insertions, 3 deletions
diff --git a/fs/coredump.c b/fs/coredump.c
index f258c17c1841..be6403b4b14b 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -872,6 +872,9 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page)
loff_t pos;
ssize_t n;
+ if (!page)
+ return 0;
+
if (cprm->to_skip) {
if (!__dump_skip(cprm, cprm->to_skip))
return 0;
@@ -884,7 +887,6 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page)
pos = file->f_pos;
bvec_set_page(&bvec, page, PAGE_SIZE, 0);
iov_iter_bvec(&iter, ITER_SOURCE, &bvec, 1, PAGE_SIZE);
- iov_iter_set_copy_mc(&iter);
n = __kernel_write_iter(cprm->file, &iter, &pos);
if (n != PAGE_SIZE)
return 0;
@@ -895,10 +897,44 @@ static int dump_emit_page(struct coredump_params *cprm, struct page *page)
return 1;
}
+/*
+ * If we might get machine checks from kernel accesses during the
+ * core dump, let's get those errors early rather than during the
+ * IO. This is not performance-critical enough to warrant having
+ * all the machine check logic in the iovec paths.
+ */
+#ifdef copy_mc_to_kernel
+
+#define dump_page_alloc() alloc_page(GFP_KERNEL)
+#define dump_page_free(x) __free_page(x)
+static struct page *dump_page_copy(struct page *src, struct page *dst)
+{
+ void *buf = kmap_local_page(src);
+ size_t left = copy_mc_to_kernel(page_address(dst), buf, PAGE_SIZE);
+ kunmap_local(buf);
+ return left ? NULL : dst;
+}
+
+#else
+
+/* We just want to return non-NULL; it's never used. */
+#define dump_page_alloc() ERR_PTR(-EINVAL)
+#define dump_page_free(x) ((void)(x))
+static inline struct page *dump_page_copy(struct page *src, struct page *dst)
+{
+ return src;
+}
+#endif
+
int dump_user_range(struct coredump_params *cprm, unsigned long start,
unsigned long len)
{
unsigned long addr;
+ struct page *dump_page;
+
+ dump_page = dump_page_alloc();
+ if (!dump_page)
+ return 0;
for (addr = start; addr < start + len; addr += PAGE_SIZE) {
struct page *page;
@@ -912,14 +948,17 @@ int dump_user_range(struct coredump_params *cprm, unsigned long start,
*/
page = get_dump_page(addr);
if (page) {
- int stop = !dump_emit_page(cprm, page);
+ int stop = !dump_emit_page(cprm, dump_page_copy(page, dump_page));
put_page(page);
- if (stop)
+ if (stop) {
+ dump_page_free(dump_page);
return 0;
+ }
} else {
dump_skip(cprm, PAGE_SIZE);
}
}
+ dump_page_free(dump_page);
return 1;
}
#endif