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a=ed25519-sha256; t=1774604917; l=1805; i=shivamkalra98@zohomail.in; s=20260212; h=from:subject:message-id; bh=LSUYWjYOjJYKYliRO3bYLhKxcMuMIBGaVN2tymO6+ew=; b=rhThTDLnB57E/DBczd8HBXwMc5oEaaeJggo8YDeT6Y5MrRyp+O/EQh7sxM1hZvm1pvxDVce7R Zy3ihFALKZ+BT2UKkAd+06tqJ3RxfEKcdMJTVjTZPZTwIrL3lutscSU X-Developer-Key: i=shivamkalra98@zohomail.in; a=ed25519; pk=9Q+S1LD/xjbjL7bEaLIlwRADBwU/6LJq7lYm8LFrkQE= X-Endpoint-Received: by B4 Relay for shivamkalra98@zohomail.in/20260212 with auth_id=633 X-Original-From: Shivam Kalra Reply-To: shivamkalra98@zohomail.in X-Rspamd-Queue-Id: 516791C000E X-Stat-Signature: 3fqswpn18gmejdbj7es7p1sybq73ajer X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1774604921-121161 X-HE-Meta: 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 kZ7DdTh7 M1gEIFvFIHINaqVcRSU2uJzonTAUwShVuUGrFcgSlWb83goXq/aWa4N35rEVlKKy0pBihpY35KmayWCPMRbTfvdJ92DifkKwNE1GhMIiF/wUYe46uQCYE3kgm47KYA7UvOK1JO834h414YIPv0ntVtv7mWgOr62uMtvnmaLrIg6bt574glSbbWrxPRmr8xWLLN5MB8AfYqaS0aCM6IPefmtXlx2G2gjKtkVUGdblOhWXEjHXHU23+z8U/GE0L81TqWoHaE1BdkvskguXHlGEahSfsnizr8vRgZemzmicN/RMVWDGDEYNaO0M+eo/gGvOF7O6Rbb5ubUFiDmm6QLVt6JrccqP53Cv+aOrdVQt9eY2SsqM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Shivam Kalra When growing an existing vmalloc allocation in-place, zero the newly exposed memory region [old_size, size) if the caller requested it via __GFP_ZERO (checked via want_init_on_alloc(flags)). Previously, the code assumed that the unused capacity in the vm_struct was already zeroed either at initial allocation time or during a prior shrink. However, if an intermediate shrink operation occurred without __GFP_ZERO and without init_on_free enabled, the "freed" portion of the allocation would retain its old data. If a subsequent grow-in-place operation then explicitly requests __GFP_ZERO, failing to zero the memory here would violate the allocation flags and leak the previously discarded, potentially sensitive data. Signed-off-by: Shivam Kalra --- mm/vmalloc.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 133c3b0418fe..ddb689bf9ba5 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -4368,13 +4368,16 @@ void *vrealloc_node_align_noprof(const void *p, size_t size, unsigned long align * We already have the bytes available in the allocation; use them. */ if (size <= (size_t)vm->nr_pages << PAGE_SHIFT) { - /* - * No need to zero memory here, as unused memory will have - * already been zeroed at initial allocation time or during - * realloc shrink time. - */ vm->requested_size = size; kasan_vrealloc(p, old_size, size); + + /* + * Zero the newly exposed bytes if requested. + * The region [old_size, size) may contain stale data from + * a previous shrink that did not use __GFP_ZERO. + */ + if (want_init_on_alloc(flags)) + memset((void *)p + old_size, 0, size - old_size); return (void *)p; } -- 2.43.0