linux-kernel - [tip:efi/urgent] efi: Let kmemleak ignore false positives

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Message-ID: <tip-a0fc5578f1d63ba6e80d9509991b4c14f6eaf488@git.kernel.org>
Date:   Mon, 17 Dec 2018 10:15:53 -0800
From:   tip-bot for Qian Cai <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     ard.biesheuvel@...aro.org, luto@...nel.org, cai@....us,
        riel@...riel.com, dave.hansen@...ux.intel.com,
        torvalds@...ux-foundation.org, mingo@...nel.org, hpa@...or.com,
        peterz@...radead.org, linux-kernel@...r.kernel.org, bp@...en8.de,
        tglx@...utronix.de, xypron.glpk@....de
Subject: [tip:efi/urgent] efi: Let kmemleak ignore false positives

Commit-ID:  a0fc5578f1d63ba6e80d9509991b4c14f6eaf488
Gitweb:     https://git.kernel.org/tip/a0fc5578f1d63ba6e80d9509991b4c14f6eaf488
Author:     Qian Cai <cai@....us>
AuthorDate: Mon, 17 Dec 2018 19:02:13 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 17 Dec 2018 19:12:47 +0100

efi: Let kmemleak ignore false positives

Address this kmemleak false positive :

  unreferenced object 0xffff8096c1acf580 (size 128):
    comm "swapper/63", pid 0, jiffies 4294937418 (age 1201.230s)
    hex dump (first 32 bytes):
      80 87 b5 c1 96 00 00 00 00 00 cc c2 16 00 00 00  ................
      00 00 01 00 00 00 00 00 6b 6b 6b 6b 6b 6b 6b 6b  ........kkkkkkkk
    backtrace:
      [<000000001d2549ba>] kmem_cache_alloc_trace+0x430/0x500
      [<0000000093a6dfab>] efi_mem_reserve_persistent+0x50/0xf8
      [<000000000a730828>] its_cpu_init_lpis+0x394/0x4b8
      [<00000000edf04e07>] its_cpu_init+0x104/0x150
      [<000000004d0342c5>] gic_starting_cpu+0x34/0x40
      [<000000005d9da772>] cpuhp_invoke_callback+0x228/0x1d68
      [<0000000061eace9b>] notify_cpu_starting+0xc0/0x118
      [<0000000048bc2dc5>] secondary_start_kernel+0x23c/0x3b0
      [<0000000015137d6a>] 0xffffffffffffffff

  efi_mem_reserve_persistent+0x50/0xf8:
  kmalloc at include/linux/slab.h:546
  (inlined by) efi_mem_reserve_persistent at drivers/firmware/efi/efi.c:979

It's allocated by this line:

  rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);

Kmemleak has a known limitation that can only track pointers in the kernel
virtual space. Hence, it will report false positives due to "rsv" will only
reference to other physical addresses:

  rsv->next = efi_memreserve_root->next;
  efi_memreserve_root->next = __pa(rsv);

So tell kmemleak to ignore the 'rsv' object.

 [ mingo: Improved the changelog. ]

Signed-off-by: Qian Cai <cai@....us>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Heinrich Schuchardt <xypron.glpk@....de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-efi@...r.kernel.org
Link: http://lkml.kernel.org/r/20181217180214.9436-2-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 drivers/firmware/efi/efi.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 415849bab233..7fcfe8a7ae98 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -31,6 +31,7 @@
 #include <linux/acpi.h>
 #include <linux/ucs2_string.h>
 #include <linux/memblock.h>
+#include <linux/kmemleak.h>
 
 #include <asm/early_ioremap.h>
 
@@ -1000,6 +1001,8 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 	if (!rsv)
 		return -ENOMEM;
 
+	kmemleak_ignore(rsv);
+
 	rsv->base = addr;
 	rsv->size = size;