linux.git/fs/pstore, branch v5.1

pstore/ram: Avoid needless alloc during header write

2019-02-12T21:45:53+00:00

Since the header is a fixed small maximum size, just use a stack variable
to avoid memory allocation in the write path.

Signed-off-by: Kees Cook

pstore/ram: Add kmsg hlen zero check to ramoops_pstore_write()

2019-02-12T20:38:54+00:00

If zero-length header happened in ramoops_write_kmsg_hdr(), that means
we will not be able to read back dmesg record later, since it will be
treated as invalid header in ramoops_pstore_read(). So we should not
execute the following code but return the error.

Signed-off-by: Yue Hu 
Signed-off-by: Kees Cook

pstore/ram: Move initialization earlier

2019-02-12T20:10:43+00:00

Since only one single ramoops area allowed at a time, other probes
(like device tree) are meaningless, as it will waste CPU resources.
So let's check for being already initialized first.

Signed-off-by: Yue Hu 
Signed-off-by: Kees Cook

pstore: Avoid writing records with zero size

2019-02-12T20:09:49+00:00

Sometimes pstore_console_write() will write records with zero size
to persistent ram zone, which is unnecessary. It will only increase
resource consumption. Also adjust ramoops_write_kmsg_hdr() to have
same logic if memory allocation fails.

Signed-off-by: Yue Hu 
Signed-off-by: Kees Cook

pstore/ram: Replace dummy_data heap memory with stack memory

2019-01-22T03:32:17+00:00

In ramoops_register_dummy() dummy_data is allocated via kzalloc()
then it will always occupy the heap space after register platform
device via platform_device_register_data(), but it will not be
used any more. So let's free it for system usage, replace it with
stack memory is better due to small size.

Signed-off-by: Yue Hu 
[kees: add required memset and adjust sizeof() argument]
Signed-off-by: Kees Cook

pstore/ram: Avoid allocation and leak of platform data

2019-01-20T22:44:52+00:00

Yue Hu noticed that when parsing device tree the allocated platform data
was never freed. Since it's not used beyond the function scope, this
switches to using a stack variable instead.

Reported-by: Yue Hu 
Fixes: 35da60941e44 ("pstore/ram: add Device Tree bindings")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook

pstore/ram: Fix console ramoops to show the previous boot logs

2019-01-17T17:14:06+00:00

commit b05c950698fe ("pstore/ram: Simplify ramoops_get_next_prz()
arguments") changed update assignment in getting next persistent ram zone
by adding a check for record type. But the check always returns true since
the record type is assigned 0. And this breaks console ramoops by showing
current console log instead of previous log on warm reset and hard reset
(actually hard reset should not be showing any logs).

Fix this by having persistent ram zone type check instead of record type
check. Tested this on SDM845 MTP and dragonboard 410c.

Reproducing this issue is simple as below:

1. Trigger hard reset and mount pstore. Will see console-ramoops
   record in the mounted location which is the current log.

2. Trigger warm reset and mount pstore. Will see the current
   console-ramoops record instead of previous record.

Fixes: b05c950698fe ("pstore/ram: Simplify ramoops_get_next_prz() arguments")
Signed-off-by: Sai Prakash Ranjan 
Acked-by: Joel Fernandes (Google) 
[kees: dropped local variable usage]
Signed-off-by: Kees Cook

Remove 'type' argument from access_ok() function

2019-01-04T02:57:57+00:00

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds

pstore/ram: Avoid NULL deref in ftrace merging failure path

2018-12-04T01:11:02+00:00

Given corruption in the ftrace records, it might be possible to allocate
tmp_prz without assigning prz to it, but still marking it as needing to
be freed, which would cause at least a NULL dereference.

smatch warnings:
fs/pstore/ram.c:340 ramoops_pstore_read() error: we previously assumed 'prz' could be null (see line 255)

https://lists.01.org/pipermail/kbuild-all/2018-December/055528.html

Reported-by: Dan Carpenter 
Fixes: 2fbea82bbb89 ("pstore: Merge per-CPU ftrace records into one")
Cc: "Joel Fernandes (Google)" 
Signed-off-by: Kees Cook

pstore: Convert buf_lock to semaphore

2018-12-04T01:11:02+00:00

Instead of running with interrupts disabled, use a semaphore. This should
make it easier for backends that may need to sleep (e.g. EFI) when
performing a write:

|BUG: sleeping function called from invalid context at kernel/sched/completion.c:99
|in_atomic(): 1, irqs_disabled(): 1, pid: 2236, name: sig-xstate-bum
|Preemption disabled at:
|[] pstore_dump+0x72/0x330
|CPU: 26 PID: 2236 Comm: sig-xstate-bum Tainted: G      D           4.20.0-rc3 #45
|Call Trace:
| dump_stack+0x4f/0x6a
| ___might_sleep.cold.91+0xd3/0xe4
| __might_sleep+0x50/0x90
| wait_for_completion+0x32/0x130
| virt_efi_query_variable_info+0x14e/0x160
| efi_query_variable_store+0x51/0x1a0
| efivar_entry_set_safe+0xa3/0x1b0
| efi_pstore_write+0x109/0x140
| pstore_dump+0x11c/0x330
| kmsg_dump+0xa4/0xd0
| oops_exit+0x22/0x30
...

Reported-by: Sebastian Andrzej Siewior 
Fixes: 21b3ddd39fee ("efi: Don't use spinlocks for efi vars")
Signed-off-by: Kees Cook