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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
	Rob Herring <robh+dt@kernel.org>,
	Frank Rowand <frowand.list@gmail.com>,
	Grant Likely <grant.likely@linaro.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	Geert Uytterhoeven <geert@linux-m68k.org>
Subject: [PATCH] of: overlay: Fix uninitialized vars in dup_and_fixup_symbol_prop()
Date: Sun, 10 Sep 2017 12:26:04 +0200	[thread overview]
Message-ID: <1505039164-25468-1-git-send-email-geert@linux-m68k.org> (raw)

With gcc 4.1.2:

    drivers/of/overlay.c: In function ‘dup_and_fixup_symbol_prop’:
    drivers/of/overlay.c:108: warning: ‘overlay_name_len’ may be used uninitialized in this function
    drivers/of/overlay.c:100: warning: ‘ovinfo’ may be used uninitialized in this function

Indeed, if ov->count == 0, both variables are uninitialized, which may
lead to a crash when dereferencing ovinfo later.

Currently this is a false positive, as the sole creator of of_overlay
structures (of_build_overlay_info(), introduced in commit
7518b5890d8ac366 ("of/overlay: Introduce DT overlay support") checks for
this.

To prevent future issues, add a check for a zero ov->count to
dup_and_fixup_symbol_prop().  Note that this does not get rid of the
actual compiler warning.

Fixes: d1651b03c2df75db ("of: overlay: add overlay symbols to live device tree")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 drivers/of/overlay.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 8ecfee31ab6d3874..ebe19e0f8e4d1f4b 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -108,7 +108,7 @@ static struct property *dup_and_fixup_symbol_prop(struct of_overlay *ov,
 	int overlay_name_len;
 	int target_path_len;
 
-	if (!prop->value)
+	if (!ov->count || !prop->value)
 		return NULL;
 	symbol_path = prop->value;
 
-- 
2.7.4

             reply	other threads:[~2017-09-10 10:26 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-10 10:26 Geert Uytterhoeven [this message]
2017-09-19 17:27 ` [PATCH] of: overlay: Fix uninitialized vars in dup_and_fixup_symbol_prop() Rob Herring
2017-09-19 18:27 ` Frank Rowand
2017-09-19 19:15   ` Rob Herring
2017-09-19 20:16   ` Geert Uytterhoeven
2017-09-20  0:20     ` Frank Rowand

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