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CVE PROGRAM SOURCE RECORD7.1 High

CVE-2026-64496

iio: event: Fix event FIFO reset race

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Status
Published
Published
Updated
Assigning organization
Linux

Description

In the Linux kernel, the following vulnerability has been resolved: iio: event: Fix event FIFO reset race `iio_event_getfd()` creates the event file descriptor with `anon_inode_getfd()`, which allocates a new fd, creates the anonymous file and installs it in the process fd table before returning to the caller. The IIO code resets the event FIFO after `anon_inode_getfd()` has returned, but before `IIO_GET_EVENT_FD_IOCTL` has copied the fd number to userspace. But since fd tables are shared between threads, another thread can guess the newly allocated fd number and issue a `read()` on it as soon as the fd has been installed. This means the `kfifo_to_user()` in `iio_event_chrdev_read()` can run in parallel with the `kfifo_reset_out()` in `iio_event_getfd()`. The kfifo documentation says that `kfifo_reset_out()` is only safe when it is called from the reader thread and there is only one concurrent reader. Otherwise it is dangerous and must be handled in the same way as `kfifo_reset()`. If that happens, `kfifo_to_user()` can advance the FIFO `out` index based on state from before the reset, after the reset has already moved the `out` index to the current `in` index. That can leave the FIFO with an `out` index past the `in` index. A later `read()` can then see an underflowed FIFO length and copy more data than the event FIFO buffer contains. This can result in an out-of-bounds read and leak adjacent kernel memory to userspace. Move the FIFO reset before `anon_inode_getfd()`. At that point the event fd is marked busy, but the new fd has not been installed yet, so userspace cannot access it while the FIFO is reset.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < 9dc84ba4be5bbeb29ee49efe6cea2cb32c461424affected
  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < d16a702ca7d29c0b7a9b509339d1b044a1cadb32affected
  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < a13ef1adbc62085b21b546b07b0be7e2fbf52150affected
  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < 0d4a646d7f87ea3625fafe387043fddc6a2f5e7faffected
  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < 72c6aa8e0d74eab91b8694cde97dec088c248feeaffected
  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < 9edefd4c56bee3fe331e0355d1f10a533134999daffected
  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < f187dc5a4c4846ffa07d9bda6e760837ed005574affected
  • b91accafbb1031b80d22ad83576877ff2f8b4774 to < af791d295737ea6b6ff2c8d8488462a49c14af01affected

Linux Linux

Default version status: affected

  • 3.15affected
  • 0 to < 3.15unaffected
  • 5.10.261 to ≤ 5.10.*unaffected
  • 5.15.212 to ≤ 5.15.*unaffected
  • 6.1.178 to ≤ 6.1.*unaffected
  • 6.6.145 to ≤ 6.6.*unaffected
  • 6.12.96 to ≤ 6.12.*unaffected
  • 6.18.39 to ≤ 6.18.*unaffected
  • 7.1.4 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References