Messages in this thread | | | From | Kalesh Singh <> | Date | Wed, 17 Nov 2021 16:17:33 -0800 | Subject | Re: [GIT PULL] tracing: Fix double free bug |
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On Wed, Nov 17, 2021 at 4:00 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > On Wed, 17 Nov 2021 15:38:59 -0800 > Linus Torvalds <torvalds@linux-foundation.org> wrote: > > > On Wed, Nov 17, 2021 at 3:19 PM Steven Rostedt <rostedt@goodmis.org> wrote: > > > > > > On error, the operands and the histogram expression are destroyed, > > > but since the destruction is recursive, do not destroy the operands > > > if they already belong to the expression that is about to be destroyed. > > > > Honestly, this seems horribly ugly. > > I guess we have a difference in opinion to what is ugly, as the v1 version > of Kalesh's patch was closer to yours, and I hated the complexity of having > to know when to to call what. Because the logic is not that simple. > > See https://lore.kernel.org/all/20211117021223.2137117-1-kaleshsingh@google.com/ > > > > > The problem seems to be that the "goto error" cases are simply just wrong. > > > > Why isn't the fix to make the error cases be the right ones, instead > > of having one odd error case that then has to do some magic things to > > not free the wrong things? > > > > The patch ends up a bit bigger, mainly because I renamed the different > > "free" cases, and because I made the non-freeing ones just return the > > error directly. > > I agree with the first part of your patch, which was not the reason for > being the cause of the bug. > > > > > Something like this (UNTESTED!) patch, IOW? > > But the part after the expr is allocated gets a bit more tricky, and that > is why I requested that logic, namely due to the "combine_consts" case. But > as the expr->operand[]s are NULL'd and the operand*s are destroyed, I guess > it's still fine with just freeing the expr if we add an error case there. > > Kalesh, care to spin a v3 implementing Linus's solution?
Hi Steve,
Yes I'll resend a new version, more in line to Linus suggestion.
Thanks, Kalesh > > -- Steve
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