The branch main has been updated by kbowling: URL: https://cgit.FreeBSD.org/src/commit/?id=74c539fd1cefdbc993411274c613434c3f23b4b1
commit 74c539fd1cefdbc993411274c613434c3f23b4b1 Author: Kevin Bowling <[email protected]> AuthorDate: 2026-08-27 14:06:55 +0000 Commit: Kevin Bowling <[email protected]> CommitDate: 2026-09-03 04:03:32 +0000 tpm20: Move user copies outside the lifecycle lock The TPM 2.0 character-device methods held the global device lock while uiomove() accessed user memory. User page faults could therefore delay suspend or detach even though the read response was already buffered. Add a per-open sleepable lock to serialize operations on each response buffer. Stage commands under that lock before acquiring the device lock, and copy them into the response buffer only after the lifecycle checks succeed. This preserves an unread response when suspend or detach rejects a write. Release the device lock before copying buffered responses out. Also advance the response offset by the bytes actually copied when uiomove() returns after a partial transfer. Validated on an Intel TPM 2.0 TIS device. PCR reads and GetRandom passed under 16-process mixed command load. A response was consumed correctly in 5-byte, 7-byte, and remainder reads. Module unload/reload recreated the device and entropy source without lock diagnostics. Source inspection confirmed rejected writes preserve unread responses. Reviewed by: kevans MFC after: 2 weeks Sponsored by: BBOX.io Differential Revision: https://reviews.freebsd.org/D59245 --- sys/dev/tpm/tpm20.c | 37 +++++++++++++++++++++++++++++-------- sys/dev/tpm/tpm20.h | 1 + 2 files changed, 30 insertions(+), 8 deletions(-) diff --git a/sys/dev/tpm/tpm20.c b/sys/dev/tpm/tpm20.c index bebf0af400fa..6c96f1ce848d 100644 --- a/sys/dev/tpm/tpm20.c +++ b/sys/dev/tpm/tpm20.c @@ -86,6 +86,7 @@ tpm20_read(struct cdev *dev, struct uio *uio, int flags) struct tpm_priv *priv; size_t bytes_to_transfer; size_t offset; + ssize_t resid; int result; sc = (struct tpm_sc *)dev->si_drv1; @@ -93,27 +94,36 @@ tpm20_read(struct cdev *dev, struct uio *uio, int flags) if (result != 0) return (result); + sx_xlock(&priv->io_lock); sx_xlock(&sc->dev_lock); if (atomic_load_bool(&sc->dying)) { result = ENXIO; - goto out; + goto out_locked; } if (sc->suspended) { result = EBUSY; - goto out; + goto out_locked; } offset = priv->offset; bytes_to_transfer = MIN(priv->len, uio->uio_resid); + sx_xunlock(&sc->dev_lock); + if (bytes_to_transfer > 0) { - result = uiomove((caddr_t) priv->buf + offset, bytes_to_transfer, uio); + resid = uio->uio_resid; + result = uiomove((caddr_t)priv->buf + offset, + (int)bytes_to_transfer, uio); + bytes_to_transfer = resid - uio->uio_resid; priv->offset += bytes_to_transfer; priv->len -= bytes_to_transfer; } else { result = 0; } + sx_xunlock(&priv->io_lock); + return (result); -out: +out_locked: sx_xunlock(&sc->dev_lock); + sx_xunlock(&priv->io_lock); return (result); } @@ -122,6 +132,7 @@ tpm20_write(struct cdev *dev, struct uio *uio, int flags) { struct tpm_sc *sc; struct tpm_priv *priv; + uint8_t *command; size_t byte_count; int result; @@ -143,6 +154,12 @@ tpm20_write(struct cdev *dev, struct uio *uio, int flags) return (E2BIG); } + command = malloc(byte_count, M_TPM20, M_WAITOK); + sx_xlock(&priv->io_lock); + result = uiomove(command, byte_count, uio); + if (result != 0) + goto out_priv; + sx_xlock(&sc->dev_lock); if (atomic_load_bool(&sc->dying)) { result = ENXIO; @@ -153,14 +170,16 @@ tpm20_write(struct cdev *dev, struct uio *uio, int flags) goto out; } - result = uiomove(priv->buf, byte_count, uio); - if (result != 0) - goto out; - + memcpy(priv->buf, command, byte_count); result = TPM_TRANSMIT(sc->dev, priv, byte_count); out: sx_xunlock(&sc->dev_lock); + if (result != 0) + uio->uio_resid = byte_count; +out_priv: + sx_xunlock(&priv->io_lock); + free(command, M_TPM20); return (result); } @@ -170,6 +189,7 @@ tpm20_priv_alloc(void) struct tpm_priv *priv; priv = malloc(sizeof (*priv), M_TPM20, M_WAITOK | M_ZERO); + sx_init(&priv->io_lock, "TPM per-open I/O lock"); return (priv); } @@ -178,6 +198,7 @@ tpm20_priv_dtor(void *data) { struct tpm_priv *priv = data; + sx_destroy(&priv->io_lock); free(priv, M_TPM20); } diff --git a/sys/dev/tpm/tpm20.h b/sys/dev/tpm/tpm20.h index 1d7a11265b02..f210cd84c331 100644 --- a/sys/dev/tpm/tpm20.h +++ b/sys/dev/tpm/tpm20.h @@ -110,6 +110,7 @@ MALLOC_DECLARE(M_TPM20); struct tpm_priv { + struct sx io_lock; uint8_t buf[TPM_BUFSIZE]; size_t offset; size_t len;
