patchSimulavr: an AVR simulator - Patches: patch #7078, fix potential string overflows in...

 
 

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patch #7078: fix potential string overflows in 0.1.2.6

Submitted by:  Juergen Weigert <jnweiger>
Submitted on:  Sun 31 Jan 2010 12:19:33 PM UTC  
 
Category: NonePriority: 5 - Normal
Status: NonePrivacy: Public
Assigned to: NoneOpen/Closed: Open
Component Version: simulavr

Sun 31 Jan 2010 11:39:22 PM UTC, comment #2:

Yes, you did it right. I only went after the obvious. Sorry.

strncat() should not be used anyway. It was designed to fool the user. Nobody would assume that POSIX blessed an interface where both caller and function would need to count the bytes.

Juergen Weigert <jnweiger>
Sun 31 Jan 2010 12:41:29 PM UTC, comment #1:

Nice catch. (Oh those pesky C string functions. How difficult to get right. And how boring.)

However the strncat() copies the specified number of bytes plus NUL byte. See wikipedia http://en.wikipedia.org/wiki/Strcat#strncat
"Common mistakes are..."
In the original patch it overwrites one byte. This new one does not, I hope.

(file #19585)

Petr Hluzin <petrh>
Project Member
Sun 31 Jan 2010 12:19:33 PM UTC, original submission:

I've compiled with latest gcc-4.4.1 and at extra mean warning levels. This is what I found:

old style flex output must be pampered with to allow ignoring returnvalue of fwrite().
strncat() third parameter must be remaining size in buffer, not total size().

Juergen Weigert <jnweiger>

 

Attached Files
file #19585:  happy_gcc_v2.patch added by petrh (2kB - text/x-diff - file #19581 + fixed 1B overwrite)
file #19581:  happy_gcc.patch added by jnweiger (2kB - text/x-patch)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -unavailable- added by petrh (Updated the item)
  • -unavailable- added by jnweiger (Submitted the item)
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    Follow 2 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sun 31 Jan 2010 12:41:29 PM UTCpetrhAttached File-=>Added happy_gcc_v2.patch, #19585
    Sun 31 Jan 2010 12:19:33 PM UTCjnweigerAttached File-=>Added happy_gcc.patch, #19581

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