diff options
Diffstat (limited to 'lib/libc')
| -rw-r--r-- | lib/libc/stdlib/malloc.3 | 76 |
1 files changed, 33 insertions, 43 deletions
diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3 index 08318c35b90..8eeea6e58cb 100644 --- a/lib/libc/stdlib/malloc.3 +++ b/lib/libc/stdlib/malloc.3 @@ -30,9 +30,9 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.\" $OpenBSD: malloc.3,v 1.52 2008/05/20 11:25:26 jmc Exp $ +.\" $OpenBSD: malloc.3,v 1.53 2008/07/28 19:53:03 otto Exp $ .\" -.Dd $Mdocdate: May 20 2008 $ +.Dd $Mdocdate: July 28 2008 $ .Dt MALLOC 3 .Os .Sh NAME @@ -244,16 +244,18 @@ If the machine is paging a lot this may help a bit. .It Cm J .Dq Junk . Fill some junk into the area allocated. -Currently junk is bytes of 0xd0; this is pronounced +Currently junk is bytes of 0xd0 when allocating; this is pronounced .Dq Duh . \&:-) +Freed chunks are filled with 0xdf. .It Cm N Do not output warning messages when encountering possible corruption or bad pointers. .It Cm P -.Dq Pointer Protection . -Pointer sized allocations are aligned to the end of a page to catch -sizeof(ptr) errors where sizeof(*ptr) is meant. +.Dq Move allocations within a page. +Allocations larger than half a page but smaller that a page +are aligned to the end of a page to catch buffer overruns in more +cases. .It Cm R .Dq realloc . Always reallocate when @@ -278,6 +280,9 @@ including in the source: extern char *malloc_options; malloc_options = "X"; .Ed +.Pp +Note that this will cause code that is supposed to handle +out-of-memory conditions gracefully to abort instead. .It Cm Z .Dq Zero . Fill some junk into the area allocated (see @@ -302,7 +307,7 @@ flags are mostly for testing and debugging. If a program changes behavior if either of these options are used, it is buggy. .Pp -The default number of free pages cached is 16. +The default number of free pages cached is 64. .Sh RETURN VALUES The .Fn malloc @@ -357,13 +362,7 @@ the process. .Pp Here is a brief description of the error messages and what they mean: .Bl -tag -width Ds -.It Dq (ES): mumble mumble mumble -.Fn malloc -has been compiled with -.Dv \&-DEXTRA_SANITY -and something looks fishy in there. -Consult sources and/or wizards. -.It Dq allocation failed +.It Dq out of memory If the .Cm A option is specified it is an error for @@ -373,47 +372,32 @@ or .Fn realloc to return .Dv NULL . -.It Dq mmap(2) failed, check limits. +.It Dq malloc init mmap failed This is a rather weird condition that is most likely to indicate a seriously overloaded system or a ulimit restriction. -.It Dq freelist is destroyed. -.Fn malloc Ns 's -internal freelist has been stomped on. +.It any other error +.Fn malloc +detected an internal error; +consult sources and/or wizards. .El .Pp Here is a brief description of the warning messages and what they mean: .Bl -tag -width Ds -.It Dq chunk/page is already free. +.It Dq bogus pointer (double free?) +An attempt to +.Fn free +or +.Fn realloc +an unallocated pointer was made. +.It Dq chunk is already free There was an attempt to free a chunk that had already been freed. -.It Dq junk pointer, too high to make sense. -The pointer doesn't make sense. -It's above the area of memory that -.Fn malloc -knows something about. -This could be a pointer from some -.Xr mmap 2 'ed -memory. -.It Dq junk pointer, too low to make sense. -The pointer doesn't make sense. -It's below the area of memory that -.Fn malloc -knows something about. -This pointer probably came from your data or bss segments. -.It Dq malloc() has never been called. -Nothing has ever been allocated, yet something is being freed or -realloc'ed. -.It Dq modified (chunk-/page-) pointer. +.It Dq modified (chunk-) pointer The pointer passed to .Fn free or .Fn realloc has been modified. -.It Dq pointer to wrong page. -The pointer that -.Fn malloc -is trying to free is not pointing to -a sensible page. -.It Dq recursive call. +.It Dq recursive call An attempt was made to call recursively into these functions, i.e., from a signal handler. This behavior is not supported. @@ -428,6 +412,12 @@ functions nor utilize any other functions which may call routines). .It Dq unknown char in MALLOC_OPTIONS We found something we didn't understand. +.It Dq malloc cache overflow/underflow +The internal malloc page cache has been corrupted. +.It Dq malloc free slot lost +The internal malloc page cache has been corrupted. +.It Dq guard size +An inconsistent guard size was detected. .El .Sh SEE ALSO .Xr brk 2 , |