Bug #9011: rb_fstring unsafe to use in general case

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: trunk
• Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN

[normalperson (Eric Wong)]

I don't think the current "frozen"f in pure Ruby code is unsafe
(I haven't reproduced a crash)

But I do not think rb_fstring is generally safe for other C code, including extension authors

Consider the following case:

    fstr1 = rb_fstring(str)
    fstr1 goes out of scope
    GC mark runs ...
    fstr1 is eligible for lazy sweep
    fstr2 = rb_fstring(str)
    fstr2 is identical to fstr1
    fstr1 is swept (rb_str_free)
    fstr2 use attempted -> crash

I extracted this bug report from Feature #8998, where I showed a patch
which exposes this bug during "make check"

[ko1 (Koichi Sasada)]

Nobu's patch r43210 may solve this problem. Could you verify it?

BTW, I don't like this fix. I'll try fix by another way.

[normalperson (Eric Wong)]

"ko1 (Koichi Sasada)" [e-mail] wrote:

Nobu's patch r43210 may solve this problem. Could you verify it?

Thanks, I did not think to update my repo :x
Anyways, r43210 works fine.

BTW, I don't like this fix. I'll try fix by another way.

I'm not sure why you don't like it, but I'll be glad to test your fix.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed