linux-kernel - [PATCH] Fix vc_screenbuf leak via con

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Date:	Mon, 13 Jul 2009 14:12:45 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	linux-kernel@...r.kernel.org
Cc:	Pekka Enberg <penberg@...helsinki.fi>
Subject: [PATCH] Fix vc_screenbuf leak via con_init()

Commit a5f4f52e replaced the alloc_bootmem() with kzalloc() but didn't
set vc_kmalloced to 1 and the memory block is later leaked. The
corresponding kmemleak trace:

unreferenced object 0xdf828000 (size 8192):
  comm "swapper", pid 0, jiffies 4294937296
  backtrace:
    [<c006d473>] __save_stack_trace+0x17/0x1c
    [<c000d869>] log_early+0x55/0x84
    [<c01cfa4b>] kmemleak_alloc+0x33/0x3c
    [<c006c013>] __kmalloc+0xd7/0xe4
    [<c00108c7>] con_init+0xbf/0x1b8
    [<c0010149>] console_init+0x11/0x20
    [<c0008797>] start_kernel+0x137/0x1e4

Signed-off-by: Catalin Marinas <catalin.marinas@....com>
Cc: Pekka Enberg <penberg@...helsinki.fi>
---

(note that detecting this requires additional kmemleak patches for early
log stack traces which are planned for the next merging window)

 drivers/char/vt.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 7947bd1..f6ac4c2 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -2881,7 +2881,7 @@ static int __init con_init(void)
 		INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
 		visual_init(vc, currcons, 1);
 		vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT);
-		vc->vc_kmalloced = 0;
+		vc->vc_kmalloced = 1;
 		vc_init(vc, vc->vc_rows, vc->vc_cols,
 			currcons || !vc->vc_sw->con_save_screen);
 	}

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