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tools/proftool: fix use-after-free

PATCH In review Vincent Stehlé 2 participants 5 messages Oct 7, 2015 – Nov 17, 2015

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Vincent Stehlé

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#0 lore raw

PATCH 1/1 tools/proftool: fix use-after-free

The read_trace_config() can dereference the line pointer after freeing it on its error path. Avoid that.

This was found by Coverity Scan.

Signed-off-by Vincent Stehl? <[email protected]>
Cc Simon Glass <[email protected]>
---
 tools/proftool.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
tools/proftool.c +3 -2
index 9ce7a77..ddf870f 100644
@@ -432,9 +432,10 @@ static int read_trace_config(FILE *fin)
 
 		err = regcomp(&line->regex, tok, REG_NOSUB);
 		if (err) {
+			int r = regex_report_error(&line->regex, err,
+						   "compile", tok);
 			free(line);
-			return regex_report_error(&line->regex, err, "compile",
-						  tok);
+			return r;
 		}
 
 		/* link this new one to the end of the list */
Signature · 1 line
2.5.3
#1 lore raw

PATCH 1/1 tools/proftool: fix use-after-free

Quoted 7 lines · Vincent Stehl?

The read_trace_config() can dereference the line pointer after freeing it on its error path. Avoid that.

This was found by Coverity Scan.

Signed-off-by Vincent Stehl? <[email protected]>
Cc Simon Glass <[email protected]>

Were you in the Coverity talk too? :) I saw this error as well today now. I was actually thinking along the lines of:

tools/proftool.c +2 -1
index 9ce7a77..b3d3057 100644
@@ -433,8 +433,9 @@ static int read_trace_config(FILE *fin)
                err = regcomp(&line->regex, tok, REG_NOSUB);
                if (err) {
                        free(line);
-                       return regex_report_error(&line->regex, err, "compile",
+                       err = regex_report_error(&line->regex, err, "compile",
                                                  tok);
+                       return err;
                }
 
                /* link this new one to the end of the list */
Signature · 8 lines
Tom
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author
#2 lore raw

PATCH 1/1 tools/proftool: fix use-after-free

On 10/07/2015 04:19 PM, Tom Rini wrote:
..

Quoted 1 line

Were you in the Coverity talk too? :)

Hi Tom,

No, I was not following that talk, sorry.

..

tools/proftool.c static int read_trace_config(FILE *fin) · line 438

Quoted 5 lines
                        free(line);
tools/proftool.c +2 -1
-                       return regex_report_error(&line->regex, err, "compile",
+                       err = regex_report_error(&line->regex, err, "compile",
                                                  tok);
+                       return err;

I am not sure you solve the problem this way. Indeed the structure pointed to by the line pointer will still have been freed before use even this way. Who knows what the memory contains when regerror() will access &line->regex, which is contained into the freed structure?

Best regards,

V.

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#3 lore raw

PATCH 1/1 tools/proftool: fix use-after-free

Quoted 7 lines · Vincent Stehl?

On 10/07/2015 04:19 PM, Tom Rini wrote:
..

Quoted 1 line

Were you in the Coverity talk too? :)

Hi Tom,

No, I was not following that talk, sorry.

Ah, coincidence then.

Quoted 11 lines

..

tools/proftool.c static int read_trace_config(FILE *fin) · line 438

Quoted 5 lines
                        free(line);
tools/proftool.c +2 -1
-                       return regex_report_error(&line->regex, err, "compile",
+                       err = regex_report_error(&line->regex, err, "compile",
                                                  tok);
+                       return err;

I am not sure you solve the problem this way. Indeed the structure pointed to by the line pointer will still have been freed before use even this way. Who knows what the memory contains when regerror() will access &line->regex, which is contained into the freed structure?

Er, bah. That's what I get for writing something in the middle of listening to a talk too. I meant to also move the free() to after the regex_report_error call and just avoid adding another variable.

Signature · 8 lines
Tom
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#4 lore raw
In reply to Vincent Stehlé
Quoted 7 lines · Vincent Stehl?

The read_trace_config() can dereference the line pointer after freeing it on its error path. Avoid that.

This was found by Coverity Scan.

Signed-off-by Vincent Stehl? <[email protected]>
Cc Simon Glass <[email protected]>

Applied to u-boot/master, thanks!

Signature · 8 lines
Tom
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