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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Peilin Ye <yepeilin.cs@gmail.com>,
	Daniel Vetter <daniel.vetter@ffwll.ch>,
	syzbot+29d4ed7f3bdedf2aa2fd@syzkaller.appspotmail.com
Subject: [PATCH 4.4 20/39] fbcon: Fix global-out-of-bounds read in fbcon_get_font()
Date: Mon, 12 Oct 2020 15:26:50 +0200	[thread overview]
Message-ID: <20201012132629.081507692@linuxfoundation.org> (raw)
In-Reply-To: <20201012132628.130632267@linuxfoundation.org>

From: Peilin Ye <yepeilin.cs@gmail.com>

commit 5af08640795b2b9a940c9266c0260455377ae262 upstream.

fbcon_get_font() is reading out-of-bounds. A malicious user may resize
`vc->vc_font.height` to a large value, causing fbcon_get_font() to
read out of `fontdata`.

fbcon_get_font() handles both built-in and user-provided fonts.
Fortunately, recently we have added FONT_EXTRA_WORDS support for built-in
fonts, so fix it by adding range checks using FNTSIZE().

This patch depends on patch "fbdev, newport_con: Move FONT_EXTRA_WORDS
macros into linux/font.h", and patch "Fonts: Support FONT_EXTRA_WORDS
macros for built-in fonts".

Cc: stable@vger.kernel.org
Reported-and-tested-by: syzbot+29d4ed7f3bdedf2aa2fd@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=08b8be45afea11888776f897895aef9ad1c3ecfd
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/b34544687a1a09d6de630659eb7a773f4953238b.1600953813.git.yepeilin.cs@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/video/console/fbcon.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -2234,6 +2234,9 @@ static int fbcon_get_font(struct vc_data
 
 	if (font->width <= 8) {
 		j = vc->vc_font.height;
+		if (font->charcount * j > FNTSIZE(fontdata))
+			return -EINVAL;
+
 		for (i = 0; i < font->charcount; i++) {
 			memcpy(data, fontdata, j);
 			memset(data + j, 0, 32 - j);
@@ -2242,6 +2245,9 @@ static int fbcon_get_font(struct vc_data
 		}
 	} else if (font->width <= 16) {
 		j = vc->vc_font.height * 2;
+		if (font->charcount * j > FNTSIZE(fontdata))
+			return -EINVAL;
+
 		for (i = 0; i < font->charcount; i++) {
 			memcpy(data, fontdata, j);
 			memset(data + j, 0, 64 - j);
@@ -2249,6 +2255,9 @@ static int fbcon_get_font(struct vc_data
 			fontdata += j;
 		}
 	} else if (font->width <= 24) {
+		if (font->charcount * (vc->vc_font.height * sizeof(u32)) > FNTSIZE(fontdata))
+			return -EINVAL;
+
 		for (i = 0; i < font->charcount; i++) {
 			for (j = 0; j < vc->vc_font.height; j++) {
 				*data++ = fontdata[0];
@@ -2261,6 +2270,9 @@ static int fbcon_get_font(struct vc_data
 		}
 	} else {
 		j = vc->vc_font.height * 4;
+		if (font->charcount * j > FNTSIZE(fontdata))
+			return -EINVAL;
+
 		for (i = 0; i < font->charcount; i++) {
 			memcpy(data, fontdata, j);
 			memset(data + j, 0, 128 - j);



  parent reply	other threads:[~2020-10-12 13:33 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-12 13:26 [PATCH 4.4 00/39] 4.4.239-rc1 review Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 01/39] gpio: tc35894: fix up tc35894 interrupt configuration Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 02/39] Input: i8042 - add nopnp quirk for Acer Aspire 5 A515 Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 03/39] drm/amdgpu: restore proper ref count in amdgpu_display_crtc_set_config Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 04/39] net: dec: de2104x: Increase receive ring size for Tulip Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 05/39] rndis_host: increase sleep time in the query-response loop Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 06/39] drivers/net/wan/lapbether: Make skb->protocol consistent with the header Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 07/39] drivers/net/wan/hdlc: Set skb->protocol before transmitting Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 08/39] nfs: Fix security label length not being reset Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 09/39] clk: samsung: exynos4: mark chipid clock as CLK_IGNORE_UNUSED Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 10/39] iommu/exynos: add missing put_device() call in exynos_iommu_of_xlate() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 11/39] i2c: cpm: Fix i2c_ram structure Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 12/39] epoll: do not insert into poll queues until all sanity checks are done Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 13/39] epoll: replace ->visited/visited_list with generation count Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 14/39] epoll: EPOLL_CTL_ADD: close the race in decision to take fast path Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 15/39] ep_create_wakeup_source(): dentry name can change under you Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 16/39] netfilter: ctnetlink: add a range check for l3/l4 protonum Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 17/39] fbdev, newport_con: Move FONT_EXTRA_WORDS macros into linux/font.h Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 18/39] Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 19/39] Revert "ravb: Fixed to be able to unload modules" Greg Kroah-Hartman
2020-10-12 13:26 ` Greg Kroah-Hartman [this message]
2020-10-12 13:26 ` [PATCH 4.4 21/39] net: wireless: nl80211: fix out-of-bounds access in nl80211_del_key() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 22/39] usermodehelper: reset umask to default before executing user process Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 23/39] platform/x86: thinkpad_acpi: initialize tp_nvram_state variable Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 24/39] platform/x86: thinkpad_acpi: re-initialize ACPI buffer size when reuse Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 25/39] driver core: Fix probe_count imbalance in really_probe() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 26/39] perf top: Fix stdio interface input handling with glibc 2.28+ Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 27/39] sctp: fix sctp_auth_init_hmacs() error path Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 28/39] team: set dev->needed_headroom in team_setup_by_port() Greg Kroah-Hartman
2020-10-12 13:26 ` [PATCH 4.4 29/39] net: team: fix memory leak in __team_options_register Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 30/39] mtd: nand: Provide nand_cleanup() function to free NAND related resources Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 31/39] xfrm: clone XFRMA_REPLAY_ESN_VAL in xfrm_do_migrate Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 32/39] xfrm: clone whole liftime_cur structure " Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 33/39] net: stmmac: removed enabling eee in EEE set callback Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 34/39] xfrm: Use correct address family in xfrm_state_find Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 35/39] bonding: set dev->needed_headroom in bond_setup_by_slave() Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 36/39] rxrpc: Fix rxkad token xdr encoding Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 37/39] rxrpc: Downgrade the BUG() for unsupported token type in rxrpc_read() Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 38/39] rxrpc: Fix server keyring leak Greg Kroah-Hartman
2020-10-12 13:27 ` [PATCH 4.4 39/39] net: usb: rtl8150: set random MAC address when set_ethernet_addr() fails Greg Kroah-Hartman
2020-10-12 18:27 ` [PATCH 4.4 00/39] 4.4.239-rc1 review Jon Hunter
2020-10-13  8:46 ` Naresh Kamboju
2020-10-13 16:38 ` Guenter Roeck
2020-10-13 18:11 ` Pavel Machek
2020-10-14  7:47   ` Greg Kroah-Hartman
2020-10-14 10:18     ` Pavel Machek
2020-10-14  1:43 ` Shuah Khan

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