>From e2e73e2bc0c5cd168de273b0fe9df1e5c48cd232 Mon Sep 17 00:00:00 2001 From: Waiman Long Date: Wed, 11 Mar 2020 11:01:59 -0400 Subject: [PATCH v2 3/3] KEYS: Use kvmalloc() to better handle large buffer allocation For large multi-page temporary buffer allocation, the security/keys subsystem don't need contiguous physical pages. It will work perfectly fine with virtually mapped pages. Replace the kmalloc() call by kvmalloc() and provide a __kvzfree() helper function to clear and free the kvmalloc'ed buffer. This will reduce the chance of memory allocation failure just because of highly fragmented pages. Suggested-by: David Howells Signed-off-by: Waiman Long --- security/keys/internal.h | 14 ++++++++++++++ security/keys/keyctl.c | 12 ++++++------ 2 files changed, 20 insertions(+), 6 deletions(-) diff --git a/security/keys/internal.h b/security/keys/internal.h index ba3e2da14cef..1b6e2d66e378 100644 --- a/security/keys/internal.h +++ b/security/keys/internal.h @@ -16,6 +16,8 @@ #include #include #include +#include +#include struct iovec; @@ -349,4 +351,16 @@ static inline void key_check(const struct key *key) #endif +/* + * Helper function to clear and free a kvmalloc'ed memory object. + */ +static inline void __kvzfree(const void *addr, size_t len) +{ + if (is_vmalloc_addr(addr)) { + memset((char *)addr, 0, len); + vfree(addr); + } else { + kzfree(addr); + } +} #endif /* _INTERNAL_H */ diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c index 662a638a680d..ca05604bc9c0 100644 --- a/security/keys/keyctl.c +++ b/security/keys/keyctl.c @@ -339,7 +339,7 @@ long keyctl_update_key(key_serial_t id, payload = NULL; if (plen) { ret = -ENOMEM; - payload = kmalloc(plen, GFP_KERNEL); + payload = kvmalloc(plen, GFP_KERNEL); if (!payload) goto error; @@ -360,7 +360,7 @@ long keyctl_update_key(key_serial_t id, key_ref_put(key_ref); error2: - kzfree(payload); + __kvzfree(payload, plen); error: return ret; } @@ -870,7 +870,7 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen) */ if (buflen && buffer && (buflen <= 0x400)) { allocbuf: - tmpbuf = kmalloc(tbuflen, GFP_KERNEL); + tmpbuf = kvmalloc(tbuflen, GFP_KERNEL); if (!tmpbuf) { ret = -ENOMEM; goto error2; @@ -892,9 +892,9 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen) * again. */ if (!tmpbuf || unlikely(ret > tbuflen)) { - tbuflen = ret; if (unlikely(tmpbuf)) - kzfree(tmpbuf); + __kvzfree(tmpbuf, tbuflen); + tbuflen = ret; goto allocbuf; } @@ -903,7 +903,7 @@ long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen) } if (tmpbuf) - kzfree(tmpbuf); + __kvzfree(tmpbuf, tbuflen); } error2: -- 2.18.1