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author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-04-07 21:23:08 +0200 |
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committer | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-04-13 13:58:57 +0200 |
commit | 5209aed5137880fa229746cb521f715e55596460 (patch) | |
tree | 887fc3a4c4269b00f739e17e379926ee77063fee /include | |
parent | a19944809fe9942e6a96292490717904d0690c21 (diff) | |
download | linux-5209aed5137880fa229746cb521f715e55596460.tar.gz |
random: allow partial reads if later user copies fail
Rather than failing entirely if a copy_to_user() fails at some point, instead we should return a partial read for the amount that succeeded prior, unless none succeeded at all, in which case we return -EFAULT as before. This makes it consistent with other reader interfaces. For example, the following snippet for /dev/zero outputs "4" followed by "1": int fd; void *x = mmap(NULL, 4096, PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); assert(x != MAP_FAILED); fd = open("/dev/zero", O_RDONLY); assert(fd >= 0); printf("%zd\n", read(fd, x, 4)); printf("%zd\n", read(fd, x + 4095, 4)); close(fd); This brings that same standard behavior to the various RNG reader interfaces. While we're at it, we can streamline the loop logic a little bit. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jann Horn <jannh@google.com> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Diffstat (limited to 'include')
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