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When ecryptfs allocates space to write crypto headers into, before copying
it out to file headers or to xattrs, it looks at the value of
crypt_stat->num_header_bytes_at_front to determine how much space it
needs. This is also used as the file offset to the actual encrypted data,
so for xattr-stored crypto info, the value was zero.
So, we kzalloc'd 0 bytes, and then ran off to write to that memory.
(Which returned as ZERO_SIZE_PTR, so we explode quickly).
The right answer is to always allocate a page to write into; the current
code won't ever write more than that (this is enforced by the
(PAGE_CACHE_SIZE - offset) length in the call to
ecryptfs_generate_key_packet_set). To be explicit about this, we now send
in a "max" parameter, rather than magically using PAGE_CACHE_SIZE there.
Also, since the pointer we pass down the callchain eventually gets the
virt_to_page() treatment, we should be using a alloc_page variant, not
kzalloc (see also
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| .. | ||
| crypto.c | ||
| debug.c | ||
| dentry.c | ||
| ecryptfs_kernel.h | ||
| file.c | ||
| inode.c | ||
| keystore.c | ||
| kthread.c | ||
| main.c | ||
| Makefile | ||
| messaging.c | ||
| miscdev.c | ||
| mmap.c | ||
| read_write.c | ||
| super.c | ||