Segfault with survreg()

[admash]

Hello!

I have run into a problem where repeated calls to try(survreg(...)) that do not converge, are causing R to segfault. The number of calls necessary to produce a segfault depends on the size of the dataset.

I have attached a .zip file with two minimal code examples that produce the crash. One uses a single row data frame, while the other uses an included ~11k data frame. The smaller data frame results in a segfault after ~250 calls, while the large data frame produces a segfault after about ~10 calls.

survreg-try-reprex.zip

The output logs for the two examples are attached here:

crash-01.log crash-02.log

I am running Arch Linux, with the following output from R.version:

> R.version

platform       x86_64-pc-linux-gnu         
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
status                                     
major          4                           
minor          4.1                         
year           2024                        
month          06                          
day            14                          
svn rev        86737                       
language       R                           
version.string R version 4.4.1 (2024-06-14)
nickname       Race for Your Life 

Please let me know if you need further information.

-admash

[admash]

This segfault has been externally verified for MacOS running on ARM as well. The provided output is attached here:

crash-03.log

[therneau]

The issue appears to be with the return value when the iteration does not converge. I'll look deeper. Data sets where survreg does not converge are very rare.

[therneau]

The survreg code first fits a model with only intercept and scale, to use as starting estimates. That iteration is failing, which leads to invalid arguments for the C routine that fails. This first bit has never failed before, and I have no checks for that. That wil be easy to fix. Failure was guarranteed in your small data set (one one obs and 2 parameters), the bigger set is an interesting puzzle to understand.

[therneau]

Now fixed. There was an error such that step halving was not properly invoked if the trial loglik was infinite. Your data set leads to a particularly bad first Newton-Raphson step.

[admash]

Thanks Terry. You remain firmly ensconced in my statistical pantheon.