dtc: Fix segfault reading powernv device tree
diff mbox series

Message ID 20180918035750.17651-1-joel@jms.id.au
State Accepted
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Series
  • dtc: Fix segfault reading powernv device tree
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Commit Message

Joel Stanley Sept. 18, 2018, 3:57 a.m. UTC
When running this command on a powernv machine, dtc crashes:

 dtc -f -I fs -O dts /sys/firmware/devicetree

Upstream has fixed the segfault but have not made a release yet so we
add the patch for now.

Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 ...001-Kill-bogus-TYPE_BLOB-marker-type.patch | 138 ++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 package/dtc/0001-Kill-bogus-TYPE_BLOB-marker-type.patch

Comments

Thomas Petazzoni Sept. 18, 2018, 7:22 p.m. UTC | #1
Hello,

On Tue, 18 Sep 2018 13:27:50 +0930, Joel Stanley wrote:
> When running this command on a powernv machine, dtc crashes:
> 
>  dtc -f -I fs -O dts /sys/firmware/devicetree
> 
> Upstream has fixed the segfault but have not made a release yet so we
> add the patch for now.
> 
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> ---
>  ...001-Kill-bogus-TYPE_BLOB-marker-type.patch | 138 ++++++++++++++++++
>  1 file changed, 138 insertions(+)
>  create mode 100644 package/dtc/0001-Kill-bogus-TYPE_BLOB-marker-type.patch

Applied to master, thanks.

Thomas
Peter Korsgaard Oct. 5, 2018, 11:27 a.m. UTC | #2
>>>>> "Joel" == Joel Stanley <joel@jms.id.au> writes:

 > When running this command on a powernv machine, dtc crashes:
 >  dtc -f -I fs -O dts /sys/firmware/devicetree

 > Upstream has fixed the segfault but have not made a release yet so we
 > add the patch for now.

 > Signed-off-by: Joel Stanley <joel@jms.id.au>

Committed to 2018.08.x, thanks.

Patch
diff mbox series

diff --git a/package/dtc/0001-Kill-bogus-TYPE_BLOB-marker-type.patch b/package/dtc/0001-Kill-bogus-TYPE_BLOB-marker-type.patch
new file mode 100644
index 000000000000..d9c660ef51ad
--- /dev/null
+++ b/package/dtc/0001-Kill-bogus-TYPE_BLOB-marker-type.patch
@@ -0,0 +1,138 @@ 
+From 9619c8619c37b9aea98100bcc15c51a5642e877e Mon Sep 17 00:00:00 2001
+From: Greg Kurz <groug@kaod.org>
+Date: Thu, 30 Aug 2018 12:01:59 +0200
+Subject: [PATCH] Kill bogus TYPE_BLOB marker type
+
+Since commit 32b9c6130762 "Preserve datatype markers when emitting dts
+format", we no longer try to guess the value type. Instead, we reuse
+the type of the datatype markers when they are present, if the type
+is either TYPE_UINT* or TYPE_STRING.
+
+This causes 'dtc -I fs' to crash:
+
+Starting program: /root/dtc -q -f -O dts -I fs /proc/device-tree
+/dts-v1/;
+
+/ {
+
+Program received signal SIGSEGV, Segmentation fault.
+__strlen_power8 () at ../sysdeps/powerpc/powerpc64/power8/strlen.S:47
+47              ld      r12,0(r4)     /* Load doubleword from memory.  */
+(gdb) bt
+#0  __strlen_power8 () at ../sysdeps/powerpc/powerpc64/power8/strlen.S:47
+#1  0x00007ffff7de3d10 in __GI__IO_fputs (str=<optimized out>,
+    fp=<optimized out>) at iofputs.c:33
+#2  0x000000001000c7a0 in write_propval (prop=0x100525e0,
+    f=0x7ffff7f718a0 <_IO_2_1_stdout_>) at treesource.c:245
+
+The offending line is:
+
+                fprintf(f, "%s", delim_start[emit_type]);
+
+where emit_type is TYPE_BLOB and:
+
+static const char *delim_start[] = {
+        [TYPE_UINT8] = "[",
+        [TYPE_UINT16] = "/bits/ 16 <",
+        [TYPE_UINT32] = "<",
+        [TYPE_UINT64] = "/bits/ 64 <",
+        [TYPE_STRING] = "",
+};
+
+/* Data blobs */
+enum markertype {
+        TYPE_NONE,
+        REF_PHANDLE,
+        REF_PATH,
+        LABEL,
+        TYPE_UINT8,
+        TYPE_UINT16,
+        TYPE_UINT32,
+        TYPE_UINT64,
+        TYPE_BLOB,
+        TYPE_STRING,
+};
+
+Because TYPE_BLOB < TYPE_STRING and delim_start[] is a static array,
+delim_start[emit_type] is 0x0. The glibc usually prints out "(null)"
+when one passes 0x0 to %s, but it seems to call fputs() internally if
+the format is exactly "%s", hence the crash.
+
+TYPE_BLOB basically means the data comes from a file and we don't know
+its type. We don't care for the former, and the latter is TYPE_NONE.
+
+So let's drop TYPE_BLOB completely and use TYPE_NONE instead when reading
+the file. Then, try to guess the data type at emission time, like the
+code already does for refs and labels.
+
+Instead of adding yet another check for TYPE_NONE, an helper is introduced
+to check if the data marker has type information, ie, >= TYPE_UINT8.
+
+Fixes: 32b9c61307629ac76c6ac0bead6f926d579b3d2c
+Suggested-by: David Gibson <david@gibson.dropbear.id.au>
+Signed-off-by: Greg Kurz <groug@kaod.org>
+Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
+Signed-off-by: Joel Stanley <joel@jms.id.au>
+---
+ data.c       | 2 +-
+ dtc.h        | 1 -
+ treesource.c | 9 +++++++--
+ 3 files changed, 8 insertions(+), 4 deletions(-)
+
+diff --git a/data.c b/data.c
+index accdfaef6668..4a204145cc7b 100644
+--- a/data.c
++++ b/data.c
+@@ -95,7 +95,7 @@ struct data data_copy_file(FILE *f, size_t maxlen)
+ {
+ 	struct data d = empty_data;
+ 
+-	d = data_add_marker(d, TYPE_BLOB, NULL);
++	d = data_add_marker(d, TYPE_NONE, NULL);
+ 	while (!feof(f) && (d.len < maxlen)) {
+ 		size_t chunksize, ret;
+ 
+diff --git a/dtc.h b/dtc.h
+index 303c2a6a73b7..51c03ef64dbe 100644
+--- a/dtc.h
++++ b/dtc.h
+@@ -82,7 +82,6 @@ enum markertype {
+ 	TYPE_UINT16,
+ 	TYPE_UINT32,
+ 	TYPE_UINT64,
+-	TYPE_BLOB,
+ 	TYPE_STRING,
+ };
+ extern const char *markername(enum markertype markertype);
+diff --git a/treesource.c b/treesource.c
+index f99544d72344..53e62036ad0e 100644
+--- a/treesource.c
++++ b/treesource.c
+@@ -133,9 +133,14 @@ static void write_propval_int(FILE *f, const char *p, size_t len, size_t width)
+ 	}
+ }
+ 
++static bool has_data_type_information(struct marker *m)
++{
++	return m->type >= TYPE_UINT8;
++}
++
+ static struct marker *next_type_marker(struct marker *m)
+ {
+-	while (m && (m->type == LABEL || m->type == REF_PHANDLE || m->type == REF_PATH))
++	while (m && !has_data_type_information(m))
+ 		m = m->next;
+ 	return m;
+ }
+@@ -225,7 +230,7 @@ static void write_propval(FILE *f, struct property *prop)
+ 		size_t chunk_len;
+ 		const char *p = &prop->val.val[m->offset];
+ 
+-		if (m->type < TYPE_UINT8)
++		if (!has_data_type_information(m))
+ 			continue;
+ 
+ 		chunk_len = type_marker_length(m);
+-- 
+2.17.1
+