Call prctl(2) with long integers, specify 5 arguments, and avoid casts #3085
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Since libc's prctl(2) wrapper is a variadic function, arguments must have the right width. Otherwise, the behavior is undefined. Also, the 5 arguments must be specified always, or the behavior is also undefined. libc reads 5 values and passes them all to the kernel, so if one is uninitialized, the kernel will receive garbagge, which could result in EINVAL (most likely), or worse, a different action. Also, avoid some casts to unsigned long, by changing the type of the parameter to some local wrappers. And use consistently 0L. 0UL is basically the same, and uses one more character. Keep it short. Link: <https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6698b096a6f5342cb9b338c237ed875a8635497a> Link: <https://lore.kernel.org/linux-man/ddbdyaiptesjalgfmztxideej67e3yaob7ucsmbf6qvriwxiif@dohhxrqgwhrf/T/#med306b5b003f9cc7cc2de69fcdd7ee2d056d0954> Cc: Xi Ruoyao <[email protected]> Signed-off-by: Alejandro Colomar <[email protected]>
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I will send a smaller v2 patch with just the change from 0 to 0L and removing the casts. I'll keep the short calls without the 0L, as @t-8ch pointed out. |
You can also create PR on github :-) |
I personally dislike the centralizing that GH represents for free software projects, and the lock-in that many projects have chosen for staying on GH. Also, I find git-send-email(1) much simpler than having to set up a GH fork, and accessing a webUI interface. On the other hand, I understand that it might be simpler for you as a reviewer, since it runs CI automatically for you. If you want me to open a PR, I can do it. By default, I prefer a mailing list. :-) |
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Mailing list is absolutely OK :-) |
Since libc's prctl(2) wrapper is a variadic function, arguments must have the right width. Otherwise, the behavior is undefined.
Also, the 5 arguments must be specified always, or the behavior is also undefined. libc reads 5 values and passes them all to the kernel, so if one is uninitialized, the kernel will receive garbagge, which could result in EINVAL (most likely), or worse, a different action.
Also, avoid some casts to unsigned long, by changing the type of the parameter to some local wrappers.
And use consistently 0L. 0UL is basically the same, and uses one more character. Keep it short.
Link: https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit/?id=6698b096a6f5342cb9b338c237ed875a8635497a
Link: https://lore.kernel.org/linux-man/ddbdyaiptesjalgfmztxideej67e3yaob7ucsmbf6qvriwxiif@dohhxrqgwhrf/T/#med306b5b003f9cc7cc2de69fcdd7ee2d056d0954
Cc: Xi Ruoyao [email protected]