patches: Bring back address structure length checks #56
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Commit 560e66e ("patches: Add patches for Musl compatibility") added the `src/api: Make sockets.c compatible with Musl` patch to fix the incompatibility issued build errors when building with Musl. Precisely, Musl does not define the address length fields of socket address structures: `sin_len`/`sa_len`. These structures were added with 4.3BSD-Reno, however POSIX does not require this field and therefore it is not standardized. Unfortunately, the aforementioned patch also removes some important address family length checks. For example, in the `accept()` syscall case, the address length passed as application provided argument is documented as meant to be overwritten by the kernel with the actual length of the filled-in address structure and not be relied upon by the kernel. A case where an application would pass a nonsense value for this argument can be seen in the case of `perl 5.38`, whose `strace` output contains the following: ``` accept4(3, {sa_family=AF_INET, sin_port=htons(45754), sin_addr=inet_addr("127.0.0.1")}, [4096 => 16], SOCK_CLOEXEC) = 4 ``` where the size of the address structure is passed as `4096` and then overwritten to `16`, the correct value. In order to handle such cases properly, add back those checks. Signed-off-by: Sergiu Moga <[email protected]>
eduardvintila
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May 31, 2024
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Nice catch, thanks!
Reviewed-by: Eduard Vintilă [email protected]
mariapana
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May 31, 2024
razvand
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Commit 560e66e ("patches: Add patches for Musl compatibility") added the `src/api: Make sockets.c compatible with Musl` patch to fix the incompatibility issued build errors when building with Musl. Precisely, Musl does not define the address length fields of socket address structures: `sin_len`/`sa_len`. These structures were added with 4.3BSD-Reno, however POSIX does not require this field and therefore it is not standardized. Unfortunately, the aforementioned patch also removes some important address family length checks. For example, in the `accept()` syscall case, the address length passed as application provided argument is documented as meant to be overwritten by the kernel with the actual length of the filled-in address structure and not be relied upon by the kernel. A case where an application would pass a nonsense value for this argument can be seen in the case of `perl 5.38`, whose `strace` output contains the following: ``` accept4(3, {sa_family=AF_INET, sin_port=htons(45754), sin_addr=inet_addr("127.0.0.1")}, [4096 => 16], SOCK_CLOEXEC) = 4 ``` where the size of the address structure is passed as `4096` and then overwritten to `16`, the correct value. In order to handle such cases properly, add back those checks. Signed-off-by: Sergiu Moga <[email protected]> Reviewed-by: Eduard Vintilă <[email protected]> Reviewed-by: Maria Pană <[email protected]> Approved-by: Razvan Deaconescu <[email protected]> GitHub-Closes: #56
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Commit 560e66e ("patches: Add patches for Musl compatibility") added the
src/api: Make sockets.c compatible with Muslpatch to fix the incompatibility issued build errors when building with Musl. Precisely, Musl does not define the address length fields of socket address structures:sin_len/sa_len. These structures were added with 4.3BSD-Reno, however POSIX does not require this field and therefore it is not standardized.Unfortunately, the aforementioned patch also removes some important address family length checks. For example, in the
accept()syscall case, the address length passed as application provided argument is documented as meant to be overwritten by the kernel with the actual length of the filled-in address structure and not be relied upon by the kernel. A case where an application would pass a nonsense value for this argument can be seen in the case ofperl 5.38, whosestraceoutput contains the following:where the size of the address structure is passed as
4096and then overwritten to16, the correct value.In order to handle such cases properly, add back those checks.